Recently after updating to PR1.2 I've had very very strange drainage. On 2 occassions I basically left my phone in the car, once overnight and once during work so more or less for 7-8 hours.

I had left it in Flight Mode both times, screen turned down so even the low power clock wasn't on. Yet when I went to my car the phone was off completely. I don't know why, it makes no sense to me.