To start with a baseline, I deleted the hps file for the F4F4.  In the offline practice arena, spawned an F4F4,  and hit F10.  This moved my head position all the way up.  I then paused TIR and adjusted my head position down till the sight was in the center and hit F10.  
Unpaused TIR and the head position stayed there, which was a good thing - haven't had that result yet.  
Paused TIR again and adjusted my head position a little up in the cockpit to where I like it - hit F10.  Unpaused TIR and my head position jumped to the top of the cockpit again.  Attempted again, same result.
Hitech, please see if you can duplicate this issue.