The light on my Macbook Pro keyboard keeps turning off?

You are covered by Apple Care if it's that new. From here ( http://www.apple.com/support/products/ ):

All Apple hardware comes with a one-year limited warranty and up to 90 days of complimentary telephone technical support.

But before you do that, try this:

http://gravitationalpull.net/wp/?p=443

One question - what happens when you take it into a dark room? Or cover the sensor with your finger?. I know there have been some issues of the low/ambient light sensor not sensing a 'dark' moment. The sesor itself is right next to the camera on the lid.

Find an Apple service center (either an Apple Store or a local authorized outfit) and take it there to be repaired instead. DO NOT let Best Buy try to repair it. The Geek Squad is filled with idiots. However, I don't think BB charges restocking fees on defective goods, so you may be able to exchange it without a penalty.

I don't have a certain answer for you but I have some advice...

Grab your manual and find EVERY section where it talks about the keyboard and read them. You might find it has something to do with a feature.

I had a problem with a TV power switch and thought it was faulty. One day I was checking something in the manual and discovered there was a feature I didn't know about, and no problem!

If it is as new as you say, just phone Apple. They will be glad to help you and can solve your problem in minutes. That's what their tech support is for.