I can't find anything on this issue at all, only issues similar is data counter going up, which is a seperate way of thinking in diagnosing that problem. Such as push, location settings, apps connecting etc etc. But mine seems to go up, then the last time I restarted & unplugged the charger after a full charge while using it, and poof! It goes back down. Which can fool me out of up to 300 or 400mb! Here are some screenshots. You can clearly see the time difference, I also made a call for a few min's to show the total call time going up, while data counter goes down.