title_body: S800 Reptile Matek F411 auto launch question
upvoted_answer: A possible explanation is the flight controller compensating for propeller torque.
  When a propeller spins, there is a counter-rotation applied to the aircraft (Newton's third law.) Assuming your propeller spins clockwise (viewed from behind the aircraft) this would be corrected in the air with a small amount of right roll - which is what is shown in your video. The amount of surface deflection will vary by airframe, so it is hard to judge from a  video if the amount of movement is correct.
  More info: http://ffden-2.phys.uaf.edu/webproj/211_fall_2016/Collin_Lasley/collin_lasley/torque.htm