If the battery is dying that quickly it may be the battery itself that is running hot. Not a good sign for a battery. You are under warantee so ask apple to check and either replace the battery or the machine if necessary.
It's not a bad idea to have Apple check your machine out, but while you're waiting for your Genius Bar appointment, you may want to read this article and try what it suggests:
Runaway processes not only shorten battery runtime, they also cause undue heat and, consequently, lots of fan noise.