Just got a 2013 Ford focus S Automatic. I am experiencing the react same issue as well. When I first got in the car we noticed this and the dealer wondered what it was as well. His exact words were "Haven't heard that nose before." Wasn't exactly comforting to know he had no idea what it was either. But at that point I already owned the car.
My car is doing exactly the same thing except threat that mine does it reguardless of temperature. Whatever it is it can't be good. Even of it is a servo those things eventually wear out. Cycling 20+ times didn't seem like it would be a good thing over time.