I've been through a total of 2 sets of batteries (quite a whopping amount huh) and it has happened with both. (the original batteries the wiimote came with and some duracel)
so yeah its possessed
Call in a Priest and try and exorcism. Maybe that will do the trick.
Or even better... If it happens again get a video camera out and record it. Then try sell it on E-bay for a rediculously high price.

Yeah, that last one. About a 90% chance you'll get at least $60. It doesn't rumble when its' not supposed to during games, does it?
Ya haha seems like a good plan. Besides then youll be able to buy a new one and have extra money and you can share the video on WL.
that never happened to me
Im sure some sucker will actually pay alot for a remote that rumbles when it shouldn't.. people will buy anything these days.
resynchronize it to your Wii
Never happened to me, so I can't really say how to fix it. All the aforementioned suggestions are good.
man thats random,id take it back, or take it to a exorcist
Just get it replaced, or use it on your girlfriend.
Just get it replaced, or use it on your girlfriend.
lol yeah now theres a good use...
or use it on your girlfriend.
LMAO Thats what I was thinking. 

Hey maybe I'll trade ya ;-)
>.> Can we get off the subject of using a randomly vibrating Wii remote on your girlfriends.
yeah its slightly disturbing