Mesaana and Alviarin vs. Mesaana and Sheriam

[Michael Wentz]

So, we know that Mesaana was in the White Tower, and really only interacted with Alviarin.  And every time she interacted with Alviarin, she was fully cloaked (Mask of Mirrors, weaves inverted, strength hidden, etc.).

But when Mesaana (we assume) Travels to the rebel camp to have a talk with Sheriam in Towers of Midnight, she's still disguised, but Sheriam specifically marvels at how much stronger Mesaana is than she is.

So I guess my question is WHY?  Why does she hide her strength from Alviarin and not from Sheriam?  The only thing I can think of is that the rebel camp has lots of strong channellers around, so a Forsaken-level channeller wouldn't be too out of place there, what with Nynaeve and Sharina being associated with them, especially with Mesaana being on the weaker side of the Forsaken.  But it still seems risky to me.  Mesaana's still strong than Egwene, and aside from Sharina, no one had said anything about any of the novices being stronger than Egwene.

[Michael Wentz]

Shoot, wrong forum.  I'll repost in the appropriate place, sorry!