I think she just dropped the ball or didn't care.. I'm sure plenty of Blacks have slipped up or told blatant lies but unless someone tries to verify their story they're pretty safe. And even if someone does catch them out I imagine they can spin it so it seems plausible that they didn't lie..No one really wants to believe in the BA anyway and everyone expects Aes Sedai to spin their words so getting out of a lie is probably fairly easy for them. I believe Verin just had other stuff on her mind and the question caught her off gaurd. She blurted something out but was fine with that because she new the chances of it coming back to her were slim and/or she could cover the slip up with some quick talk.