It think the fact that basically confirms there's nothing wrong with the timeline and the rumour is just a rumour among many others about the Tower (and false at this point) is the very important missing bit that is as much if not more "shocking", and that Teslyn (not to mention Mat) would have made a huge point about if she heard it: before reunification, the Tower faced a major attack from the Seanchan. When that events happen, tons and tons of pigeons from merchants and such in Tar Valon will fly to other cities with that news, and if Mat heard that, he'd swallowed his hat (that's his wife who attacked the Tower!!! Mat doesn't fully realize how committed Tuon is against Egwene, and Rand - and in how much of a political nightmare he's caught with his divided allegiances...).