I would look for a couple of things; first, see if the surface you are parked on is flat. If it's angled, the mast might want to float in that direction. Also, the straps can be adjusted on each side. What I did was to spend some time on a non-sailing day (ie; no pressure to get rigged and get out there!) raising and lowering the mast, adjusting the side straps as needed. My similiar problems disappeared after that.
Sheldon
P-18