Wii Sports bowling has a directional fix built in. If there is on pin on the left side of the lane and you try to spin in right, it will still go to the left. I know the first time I heard this I thought it was someone attention seeking but try it yourself, you'll find it impossible to aim away from the pin. When I realised it was true I was disappointed and it took a lot of shine away from Wii Sports bowling.
So your Wiimote is fine. Don't worry.