Well the best thing to do is to charge it all the way up, run it all the way down, and then right before it dies, jump in the battery use settings to see exactly what's been using it. With new software though, this is something that is a common side effect. On your next charge cycle, try fully charging the battery up with the phone powered off, then let it run down all the way until it dies completely, then charge it all the way back up again with the phone off. This should help to re-calibrate the battery and help it acclimate itself to the new software.