If you've noticed this on your phone, you may think it got fixed with 8.1.3 but that might be because you don't have location services/system services/Status bar icon turned on anymore. I've had this issue since 8.0 I think. If I have the system services part of location services status bar icon on, it is on 100% of the time 24/7 and it ends up being because motion calibration is ALWAYS running (purple arrow in the menu). Is Apple ever gonna fix that to only calibrate every so often? Yes, i could turn it off but I shouldn't have to tweak like that. Stuff should just work.