That specific case was meant as an example of an oops not a retcon, in terms of character behavior that didn't fit. E.g. we don't know for sure that Thomas and Harry didn't go to creepy island pre-Turn Coat post Small Favor but it would be damned odd that they did, so its not technically impossible. I'm saying Stannis's suspicions are very peculiar and that even Jon's is a bit of stretch if Stannis had presented evidence. It requires remembering something that few would remember while bypassing a more obvious solution that has a fmaous story connected to it. Ned's suspiscions aren't, note I didn't include him, he is expecting a conspiracy and looking and getting tidbits dropped by others.

After Ned (and Jon and presumably Stannis) did a buttload of research they found out that every recorded incident, none in living memory, had 'gold yielding to coal'. There's a famous legend everyone knows of Lann the Clever stealing the sun to make his descendants (who IIRC were female line) have golden hair. Their real daddy is mommy's twin, so there's no 'real baby daddy' features to notice, their hair blond which the lannisters are famous for having. I'll grant it isn't entirely ridicolous that Stannis might remember that his Great or great-great grand Uncle Gowen married a lannister but their only child died in infancy fifty or more years before Stannis was born so its not like he's got direct and loud examples in his own head screaming 'look at my hair color'. The error I'm pointing out is the logic chain being unrealistic, we already know they were right, but it's like the Tyrion arrest, the characters were acting very naively to act surprised by the notion that maybe a common footpad showing up with a super valuable dagger that had no practical advantage for assassination might indicate some sort of misdirection or frame. Now we can hypothesize that Stannis may have gotten a hunch or whiff of the incestuous adultery that sparked his suspiscions and he did his research and showed it Jon but my point is that just from what we know, minus our omniscient view, its a hell of a hypothesis to come up with since Stannis isn't exactly implied to have made any effort prior to his suspiscions to look up Robert's bastards beside Edric who is kind of forced into his awareness.

Again though it's the same thing with Tyrion, it's not impossible but its frankly weird that "Or perhaps someone is trying to frame him" wans't a thought that entered Cat's mind, for all Petyr led her to that, she still should have thought of it, certainly given it serious thought the moment Tyrion had, and also had a long trip after getting the dagger to think about it before Baelish planted the idea. Ditto Joffrey as the assassin's master, that's weird behavior even for a nasty snake like Joffrey, finding and sending an assassin to go back to Winterfell to kill off a second son of five kids who everyone thinks is probably going to die and considers his death a mercy. Now that's thinner but I've always found that to have a whiff of alteration from the original author plan and we do know he is willing to do that consider he outright changed things up to remove a planned five year hiatus in the storyline.

Again I wasn't specifically saying retcon, just the whole class of author errors and changes from their original plan. There's no plothole or retcon in Dresden's having two kids, which again was the original point, just that authors do change their works or make big oversights of how a character should have acted, like forgetting a power or skill they previously displayed that would instantly solve their current dilemma. In that class we have a number from GRRM, some are probably legit but likely at least some aren't. Examples include:

The original prologue, where rather than taking a more direct path back to the Wall, where his brothers who are most likely to believe tales of Others live, the lone survivor takes a longer route back around the wall or scaled it, this is actually pretty bizarre when you start thinking about the timeline for his flight, weeks, not days, and the simple fact that he could get over or around the wall all by himself implies that he could have turned around after he got south and returned to the Wall and just said he fled, got lost, and took his first chance to get the wall between him and the monsters. So he had a lot of time back in civilization to pull his head back together. Again ts not a retcon or oops necessarily but it's thin and smacks of plot-driven behavior.

The Bran climbing and skydiving with Lannister aid is a bit thin to me too but skip that.

Sansa's false memory of kissing the hound, working theory says it indicates biased narrator, but I'd gamble on 'oops' there. I also tend to think that much like Lost and X-files, where they just had mysteries they never prepped answers to, that GRRM's doen this a few times and done 'Varys Ex Machina' or Baelish Xanatos Gambit to cover him having either not thought up the mystery or needing to change it from an inconsistency.

Nobody wondering what the hell Ned's sister and 3 of the 7 Kingsguard are doing in Dorne months after King Aerys was killed. Ned went from the battle of the trident to King's landing (somehow beating Tywin Lannister to the throne room) to Storm's End to lift the Siege, to Dorne and the Tower of Joy. Word would have laready reached Dorne that Rhaegar was dead and Aerys too. Why did they stay with months to flee in once Aerys death was known? Who are they guarding her for and from? Her brother? And his army? Why did he go there with only seven dudes? He had an army presumably consisting of a lot more than seven riders or ships to carry riders. Why if it was important enough to leave 3 kingsguard did it not merit some foot troops too? And most importantly, why do people not speculate about this in the books a lot?