Well a few months ago, I plucked up the courage to retract my foreskin back so that it exposed the entire head. Since then, my foreskin hasn't been the same. Before it used to cover the head of the penis completely, but now it constantly leaves a few millimeters of the head exposed and sometimes it even retracts of its own accord (without me even being aroused)

I don't feel any pain or anything, and it is not really sensitive. It's as thought I'm partially circumcised, which I'm not.

Is this normal or is it something I should be concerned about?
I'm 15 bdw.