i figure mine was an accident
fitting in the tremolo arm with the guitar on the guitar stand
i later always fit in the arm while the guitar still in the case
i do turn it in as far as possible
but never ever over do it
i guess it was because of mismatch alignment in between while playing
also not because of aggressive playing
i use tremolo more aggressive now
when it happened years back, i was not using it too heavily
and it happened only once until now....

Mine is doing the same thing Eric Johnson Strat just about to break using 3 springs and his string set 10-50