I don't get it either. I did notice sometimes I would come back to my computer and iTunes would have an error up saying something about unable to find iPhone, or could not sync with it for some random reason, even though it wasn't plugged in, and I had never told it to sync. I think it's trying to locate it for some reason that I don't understand.
Either way though. I woke up this morning, and within a couple hours battery was down to like 85% and I hadn't even done anything. I unchecked sync over wifi, and over the next several hours the phone has only gone from 85% down to 82% with me checking things periodically.
Ok ill turn off wifi sync. tbh i don't think its a big deal,i like using a cable,10x faster.