I noticed the same thing. Although I personally don't find it a deal-breaker. I think the culprit is the fact that from my research Bose now has noise-cancellation microphones not only inside but outside of the earcups on the CQ15's, whereas the QC2's only had microphones inside the cups. The problem seems most pronounced on the CRJ during takeoff when you have lots of air coming out of the gasper vents. I like to position the vent to blow directly on my face and I think the high velocity of the air as it blows past the external microphone is causing the issue. To be honest with you after only a few trips I got used to it and now I don't even notice it anymore.

I still think overall the 15's have far superior noise-cancellation than the 2's and am quite happy with the setup.