high humidity would fix that. it happens when they are dehydrated. 65%-70% is fine. My cages stay at 60% all of the time. So if you can get it to the 60%-65% range that would be ideal.
I would give your BP a 20 minute soak in warm water
water temp in the mid 80's. remember what feels hot to you will be boiling to a cold blooded snake.
If a 20 minute soak doesn't fix it, then I would look for things in the cage that might have caused it. (by running into things)