I've experienced the phantom charge also. I fly a couple times a week and notice it mostly after I turn phone on. For example, turn phone off before flight at %50 battery. 3 hours later when I land I turn it on and am at %27 battery. If I leave it alone, it will slowly start creeping back up and within an hour or so will be %40 or higher.
The flying has nothing to do with it, just using it as an example.
Sent from my SGH-I897 using XDA