This is the first time this has ever happened. I charged it to 100% last night and then powered it off. I have not used it for exercise at all today. In fact, the activity ring says 0 out of 30. I just put if on the charger and it's at 12%. Very weird. Should I be concerned? I turned the watch on at 7:45AM and I put it on the charger at 2:50PM.