BS implied that, when he stated at a signing that:
"The black/dark aura around Rand is partially, but not entirely, an effect of True Power usage. There will be consequences from Rand's True Power use."

In another Q&A we learn:
Matt: "There was some confusion about Rand and the Dark One’s permission, so for clarification’s sake, did Rand have the Dark One’s permission to use the True Power?"
Brandon: "I have not answered that. If anyone says that I have, I have not. What I have said specifically is, this is recording [in other words, Matt has audio documentation of this - Terez]: generally one must have the Dark One’s permission to use the True Power. Semirhage believed that the Dark One had betrayed her by letting Rand use it. It is good that you have asked this so I can make sure on the record that is the answer I have given."

The question is if Rand used the TP through Moridin's link or directly tapped into the TP. In the second case he apparently would have needed the DO's permission to do that. On the other hand, if Rand channeled through the link, he basically used Moridin's ability & permission to channel the TP; this was either allowed by Moridin and/or the DO, or they were surprised by it.

Personally I believe that Moridin and the DO couldn't anticipate that Rand would be able to channel the TP through the link.