At least, Rahvin was somewhat prepared for an attack. He at least had defenses set up, and it was mentioned by Lillen Moi... er, Moghedian, that Rahvin had his own plans, or some such.

And it was my impression that Greandal was part of that Andoran trap. Not sure if this is accepted by the larger community or just my fanciful theorizing, but I believe that some of the tel'aran'rhiod attacks on Rand were directed by Greandal.

My justification for the above is Rand's wounds that weren't reversed by Rahvin's balefire, coupled with Greandal's proximity to Andor, now that we know she was Asmodean's murderer.