I have some analog HobbyKing servos that move a short distance clockwise everytime they are powered up. If you re-power them multiple times without giving a command to re-position the servo arm they can get to the end-stop and try to push against it - which is NOT good for them. This could also happen if the servo had been close to the end-stop after the final commanded movement before it wad depowered.
I asked HobbyKing about this and their guy said that the digital servos don't do this. I do have a few of their digital servos which do not move at startup which seems to confirm his advice.
...R