In reply to boulderingwannabe: sililar thing happened to me before while laybacking but foot was in a horizontal break with a massive whip crack noise. There was a big pop and my lower leg was hanging flimsy at a jaunty angle, i tried to moved it and it popped back again but felt really weak and floppy. Climbed a bit more the ret of the day, but carefully. After a day or two of keeping an eye on it, it was back to normal.
Now i sometimes (very rarely) feel twinges in my knee on big awkward egyptians and odd groove moves and know to go careful.
i hope its the same thign!