Please do an eperiment.. remove props. leave the Phantom on your table, then take off.. leave the stick free. in the resting position. turn off RC, motors keep spinning at low speed... now switch the RC back on.. the motors STOP! I wonder.. could this happen while phantom is in the air, for example if connection temporarily breaks? Nobody pulled the left stick down, only turned the RC OFF, I'M VERY scared of this, and you?