Glock 23 question: Has anybody had a problem with the locking block pin (part#36 in the exploded diagram) working its way out during firing. After putting 50 rounds through my G23 today I found that the pin had worked itself partly out on the left side. I immediately pressed it back and had no malfunctions. But if this is a recurring problem I definetly need to do something about it. Has anybody else had this happen?