Shaidar Haran could have conceivably found them, but I still think there was a reason Jordon/Brandon wrote the scene with Bair/Sorilea in.

One thing we know from the same book is that Sorilea is weak in the power but extremely gifted at copying flows she has seen even just once. I therefore find myself suspecting her. I think we'd need to go back through the series and look more closely at Bair and Sorilea's actions before jumping to the DF conclusion though. But this issue has bugged me for quite a while.