I'd like to follow up on Jamie's observation about a hard freeze. How cold does it need to be to kill this stuff? Probably, what, under 10F for a week or so with no snow cover?
I'm not a greens super, but my observation about "winter kill" of bermuda here in the South is that it is most likely to occur when there is a very wet period, followed by a hard freeze, followed by snow/ice that stays on the ground for a prolonged period. The winter kill tends to happen in shaded areas where the snow/ice hangs on longer. We rarely see winter kill from cold alone, but of course we wouldn't have prolonged periods where the ground stayed frozen.
But as long as I'm guessing...
I'd bet the bermuda that you are seeing is in areas where it is LEAST likely to encounter the conditions that would kill it off; that's why it is proliferating in some places. The places that would have the necessary conditions for winter kill of bermuda don't have any anyway. Make sense?
One cautionary note: Our super sprayed preemergent in our bermuda rough in early March as he always does. We then experienced the warmest March on record, causing the bermuda to green up much earlier than normal. The preemergent caused the rough to turn brown and appear completely dead. For about two weeks...
Now, in August, we have the thickest rough we've ever had, to the point where the mowing schedule can't even keep up with it and the penalty for being in the rough is easily a half shot.
My advice? Learn to play out of bermuda rough. I'll bet that you are going to see more and more of it; there is damn near nothing short of napalm that you could kill it with and have anything else survive.