I started playing my friend's Wii play game one day, and went to play battle tanks with my nunchuck. Then i realized, without touching anything, that the control stick is leaning slightly to the bottom left, so my tank is constantly moving no matter what.

I have no idea how this happened, any ideas how it happened, and how should i go about fixing it? I mean its not TOO bad, but it might get annoying in other games. Any ideas?