So yesterday I made a bunch of short flights with my PV w/ a friend. We drove to one spot, fly it for 5-10 minutes, drive to another place, make short flights, etc) .. and on my 2nd or 3rd flight I experienced what seemed to be a trim-drift in mid air. (is that the correct term?) After accelerating along a 400ft straight line, I slowly countered the movement to stop then centered both of the sticks... the problem was that my Phantom continued to drift slowly forward even after making the complete stop. I tried to quickly confirm this condition by moving-centering my right stick a few times, and true enough the center seem to have drifted. So I flew back to home position and landed. I 'rebooted' the PV while keeping my transmitter and wifi repeater powered on, and it showed an MC error on the APP (MC Calibration Error - or some such. I forgot the wording). I thought I was screwed if I had to drive back home to recalibrate the whole thing with Phantom Assistant. As a last effort, I shut everything off (tx, repeater, pv) and repowered them back on. This time the problem went away.