I did that once. Nothing happened.
I can't say for sure, but I can't imagine anything will happen. Hubpages has to assume that once in awhile a hubber will do that accidentally, or forget they aren't supposed to, so it is doubtful they are going to care, if they even notice, the occasional self-click. Their concern, therefore, I'd imagine is only for a repeated pattern that would suggest someone trying to cheat.