I used to have the same condition (it's not a problem in my case, just an observation) with a chain WDH. One side was always harder to hook than the other, which meant I really had to jack the hitch up to overcome the resistance. I now have an Equalizer bar WDH, a different truck, and a different TT, and have the same condition. The only thing I could think of is that since the truck is 4 wheel drive, it might be a little heavier on one side (the transfer case weights about 200lbs I think), stressing the frame just a enough to throw things off.
Just a wild guess since otherwise once set up all is well.