auto-dimming rearview mirror issue

For those of you with the the back-up camera built in to the mirror and the green LED button for the auto-dimmer, have any of you experienced the green LED out suddenly? My truck is a 2010 Sport.

I'm pretty certain the green LED light for the mirror has always been on, even during the daylight hours, since I purchased the truck. Today I noticed the green light was off, and pulled out the manual to read about it, and pressed the "auto" button in the center of the mirror to toggle through dimming on/off. Nothing I did got the green light to activate. I'm assuming that if the green light is out, the auto-dim feature will probably not work either. Has anybody run into this and/or had it fixed/replaced by Toyota? I shined a flashlight at the sensor, but the mirror did not seem to dim. Anything I could be overlooking that put this into an off mode? The sensors are not dirty.

Thanks.

John