how do I re-center my Wacom tablet pen?

I plugged my Intuos4 (m) in today, and its almost like its not centerd correctly.
like when I move it up, the curser hits the top of the screen before the pen touches the top of the tablet, and when I move it down the pen reaches the bottom before the curser.
How can I fix this? It was working fine yesterday (Like the pen and curser touched the top and bottom of the screen and tablet at the same time)

Any suggestion welcome