They weren't able to run their diag test and he wasn't sure why, so the genius just ordered me a new battery and said they'd call when it was in the store.

If it's not the battery, I can only assume it would be the charging system. He found it very strange that the cycle count was only 382 since I've had the machine almost 2 years. During they day I generally run with it plugged in, but I unplug it pretty much every night to run on battery power.