I had a problem of the Kimber sending brass back into my face and landing on top of my head, but after a thousand rounds it seemed to have stopped. Guess it was scared to have Wilson parts installed in it.
The extractor probably rotated slightly and finally started sending 'em out at the right angle. If it happens again then the extractor rotated back again. In other words, a better-fitting extractor would then be in order.
Second possibility was a burr somewhere that finally wore off.