Mine did last night while I was running. I got home and laid down to watch MNF and man it hurt for a couple hours. I could hardly move. The wife told me this happened to her a while back when she was exercising and to try to pop it. I really couldnt because it hurt to bad, but while I was laying there on the floor it just *popped* when I tried to do a sit up and all was fine. It was a really loud pop too. Has this happened to anyone else?