Why does my 4 month old Macbook Pro sleep incorrectly?

Whenever I close the lid on my macbook pro, the sleeper light still stays a solid white. The apple emblem that lights up on the cover unlights when I close the lid but after 5-10 seconds it turns back on. Eventually after 15-20 seconds it will finally shut off. It seems as if it's having sleeping problems. Do you know of any way that I can fix this?