Hi pilots, I need a little help if you can. I took my Phantom 4 out for about a 20 minute flight this morning. I noticed when I was hovering that my display on my tablet showed the aircraft at a little over 9 feet when I know it was just under 6 feet. Is there a calibration that I need to do? IMU was warmed up outside, compass not calibrated in the last 6 weeks. Thanks guys