Some clues regarding iOS 5.0.1 and battery life

I've gotten a lot of help from this site and this is my attempt at payback. I don't have a plan but I do have some facts that might help.

I have a 3gs. I upgraded to iOS 5.0 and aside from some balkiness it worked just fine. At this time, no battery issues.

When the 5.0.1 upgrade came out I installed it directly from the 3gs and not by going through iTunes. It went just fine. I can also say that no battery issues at this point. I also rebooted the 3gs just for grins.

Yesterday, I had a significant battery issue. The phone didn't get warm, but I was losing about 1% every 15-20 minutes at idle. I looked at the Diagnostics and there were many listed, perhaps 15-20.

I rebooted the 3gs and then did a hardwired iTunes sync. Afterwards, after about an hour at idle, the battery % didn't move, to the point that I thought it was stuck. 12 hours later at idle, and no diagnostics. Battery usage appears fine.

Somehow in the middle of all this I wonder if the Facebook app is in the middle of it. It was always listed as the largest process in the diagnostics. It also has quite a stack in its UI and I wonder if it could be allocating too much memory? Does iOS have safeguards against that?

My reasoning is that I would bet most iPhones have Facebook installed.

Just a guess.