Whenever I unplug the magsafe the first battery reading is always some weird number like 477:43 or 102:22 or 9:53. No matter how long I wait before looking at it (I have it to only show the icon) it's always some super high number and if I click on it a seconcd later it goes to a normal low 3 hour range time. It's never done this before today actually. It usually spends a lot of time calculating. Why's it doing this?