I think you've got this wrong, IIRC, when the party arrived in Illian they noticed the residents were acting slightly depressed and apathetic (alarm #1). A short while later, they discovered practically all of the residents were having the same dream about Sammael (although they did not know it was him) who was not even bothering to ward his dreams (alarm #2). Very shortly after, Perrin spots the Grey Men in the nick of time, there is a short ruckus and the Grey Men are dealt with (alarm #3).

Moiraine is finally convinced that they have stepped into the back garden of a Forsaken. She exits stage left, not to "look for information from unknown sources" but to mess him up. Moiraine forbids Lan to follow her as she is convinced she is going to die. (It is in this window that she discovers her target for termination is Sammael.)

Just for completeness, Perrin and Lan discover evidence of Dark Hounds near the inn and Lan runs off to Moirain anyway, saves her life and brings her back.


Moirain is s tricky one. The whole way through the story, RJ has given us mixed messages: Is she one of us? Is she one of them?
IMO, this is a perfect case of "Do you trust Dumbledore?" [Harry Potter Spoilers here if you haven't read it yet ] In the lead up of the last book, no one was sure if Snape was good or evil. The only way to decide was: Do you trust Dumbledore? Dumbledore believed Snape was good, therefore, if you trusted Dumbledore then -despite all evidence to the contrary- Snape must be good. Moiraine is a similar idea: She has a great many secrets and gives us reasons to suspect her of being BA every so often (eg, the Balefire knowledge) but you just have to decide: Do you trust Moiraine? I do, therefore -despite all evidence to the contrary- I believe Moiraine is a goodie!