Look at the surface of the L bracket where the bars rest. Is it polished equally across or only at the front edge? If it is polished evenly across the surface then the bars are resting on it just fine. If not then I would do as you mentioned and add a washer or two to get a bit more tilt to the hitch head and then lower the L bracket one notch to see if that helps.
The problems with having them not adjusted flat on the L brackets is that 1. they make more noise. 2. They do not apply sway control evenly throughout the sway event. 3. The may make the L bracket move from its' mounting position on the A frame.
It is fairly easy to adjust so there is no reason to not have it just right. It just takes a bit of time. :). The sticky at the top of the forum deals mostly with the chain type of hitch but the theory behind the the adjustments is the same.
Barney
2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch (Sold)
Not towing now.
Former tow vehicles were 2016 Ram 2500 CTD, 2002 Ford F250, 7.3 PSD, 1997 Ram 2500 5.9 gas engine