Turned on my Surface RT this morning after charging, and the battery display was showing an empty battery with a red x. I tapped the display and got a warning that said "Battery not detected". It was fully charged, so I'm confused as to why I'm getting this warning. I did a restart and the warning went away. This is the 4th time this has happened. I'm starting to wonder if I just got a bad tablet and need to exchange it for another Surface. Anyone else had this warning?