If the device is on, and I'm using it (just browsing the internet, with one tab, no other apps or desktop programs running), should the light eventually turn green? Because, I was using mine last night (just like described) and the light didn't turn green. It was always white. Perhaps it just hadn't quite reached full charge yet, but I'm just curious to know if the light only turns green if the device is off and reaches fully charge etc.?