It seems blogger Robb Allen had stored his defensive handgun for a few months, and when he finally took the gun out of the safe, he found had a problem with rust:
Oh, there’s none on the gun itself; I keep that cleaned and lightly oiled so the metal is fine. No, the rust was all in my fingers and between my ears. Months of simply not handling a gun on a regular basis saw me jerking the trigger and not being able to get on target in a timely fashion.
It happens! Shooting is a perishable skill, but regular practice is a good preservative. (Go read the whole thing.)