That's really weird.
A few things:
A) The Kindle does use energy when it is just sitting there contrary to press statements
B) The Kindle's battery indicator is... well.. not at all reliable.
Also, it could be another issue. My Kindle had a problem similar, and was fixed by reflashing the firmware. I don't remember how to do this, but you may be able to find instructions online or call Kindle support and get instructions. Fixed mine and no problems since.