Sounds a lot like turn anxiety. You are in a bit of survival mode and maybe are using too much force too abruptly. These turns should be smooth and kind of slow on the terrain you are riding. Take a deep breath, relax and slow things down a notch and see if that does not ease or correct the problem.
I agree, it only happened once or twice, I didn't even really panicked about it when it happened, i know if I look up the mountain I'll stop, so I just let it be.