As long as there is some pressure from the preload spring on the cap I wouldn't imagine it would loosen itself. A quarter turn after it has made contact with the spring I can't turn it by hand.
Exactly, under the pressure it stays put (otherwise it would not be able to adjust the tension anyways).
Btw I am liking it more and more each day. Although it feels firm since I have used it I have never experienced any spikes, pain etc. even when going over potholes and it does not effect my pedaling efficiency. It is not bouncy but it takes care of the bumps etc very well(Once I tried body float and it was vibrating a lot , I felt like I was sitting on a massage table).