I dont have an answer for ya right now on the servo. I dont know too much about them and have only really dealt with servos one time (the first time I attempted electronics which was last year).
However, I do know that the receivers have 3 control modes...latched, momentary, and toggle. This means you can program it (real easy...I was able to do it! You just use the transmitter to do this and the instructions on doing this are included) to adjust to your function. I would imagine that if you have the proper setting the servo arm would return back to resting position. I know it did on my RC car when I used it.
For instance...the receivers came in the mail, they were all programmed for the latched mode. This meant that when I pushed the button, the door actuator would do it pull function, but instead of pulling and returning back to resting, it would keep pulling. So, in order to relieve the pull function, you would have to push the buttom again to turn it "off". But, I switched to a different mode (cant remember the difference between momentary and toggle, but I used one of them, ha ha) so now when I push the button once, the door actuator pulls and then returns to normal position. Hope this helps and hopefully somebody can help you out with the servos. This would be my best shot, but like I said, I dont know too much about them...Good luck!
This servo may be too small for what you want to use it for...but just thought I'd try!