Backlight dimming problem

My new Unibody Macbook Pro is starting to have an issue with its backlight. I turned all dimming off in energy saver, and yet while I'm using it, the backlight begins to dim out, stay a few notches dimmer for about 15 seconds, then its returns to its original brightness that I set it on. This just started happening yesterday (I got the MBP for christmas), after I switched to the 9600 graphics card to see the difference in graphics. I am now back on the 9400 and it's still happening, so I dont know if there is any correlation. Has this happened to anyone else?