See the other battery post on this page. Seems to be fairly common (I've had it on 2 nooks). RAH has a method that works fine for me: After your battery drains down about 10% you can top it off through a computer USB and get the expected battery life (lose 1 or 2 percent a day).
Or you can exchange it (probably the way to go).
I'd let it go through a few charging cycles to make sure it isn't just a calibration thing, and then if the problem persists, return it or use RAH's home remedy.