Just purchased a Mavic Mini.  I've done 3 short flights with it.  It is very easy to use, takes great pix and videos.  However, the screen on my phone says it needs calibrated.  When I do the horizontal rotation, it recognizes it, then says to do the vertical rotation,  but my screen never says calibrated completed.  Am I doing something wrong, or does is really not need it since everything seems to work just fine.  Highly recommend any first timers look at this drone.