My 650 rino did it once and only once about a year ago. Same thing reboot fixed. I think the sensors need to be recalibrated, which a power down will do sort of. Or, just recalibrate using instructions that should be in the instruction manual. Be sure to be away from anything big and metallic when you do your recalibration. I can't remember off the top of my head what the steps were, but it's in the manual.
You should be able to look up YouTube videos on how to do it too.