I've had that happen a few times in the early morning harsh sunlight when approaching in it's direction. I believe it's related to the sensors being blinded/fooled. Just a tip, I was able to get home flying sideways and not directly into the sun. I'm sure I probably could have gotten in to the menus and fiddled with disabling the sensors, but in the heat of the moment it's a bit worrisome when it's far away and way up high!