I have a wireless mouse that I use now and if the batteries start to get weak or if the receiver gets moved very much the mouse does all sorts of strange things. If you have a wireless mouse I would check my batteries and the position of the receiver. Also though an older mouse even if it is wired can have worn contacts and they can lose contact with the button causing it to click on its own. Or as sometimes is my case, I finger which has some nerve damage twitches slightly causing a premature click that sometimes I am not even aware of until the lousy shot happens. For what ever reason all these things seem to happen most often when putting. So it might be part of your problem.
2 good rules of thumb when using a wireless mouse to play this game
#1 fresh batteries before the start of any important round. (I always have 2 sets charging)
#2 check the position of your receiver before any round.
Because not only can weak batteries cause premature clicks they can also cause late clicks because the mouse doesn't send to the receiver as soon as the button is released or clicked.