It is very possible if you have tightened the adjustment tight enough to make it a bit hard to manually center the hitch, which will prevent movement when starting or stopping, that the entire hitch is moving in the standard bed rails, if you have the ISR model of the Pullrite hitch. This is part of the instructions from the install manual:
Page 5
BASE RAIL FOOT ASSEMBLY
5. To minimize any forward and aft movement when towing, secure the feet as far apart, fore-to-aft, as the slot opening on the base rail will allow. If you still experience movement, consider loosening the base rail fasteners and tapping the base rails toward each other to achieve optimal positioning.
6. Torque the bolts to 75 ft. pounds.
7. An aftermarket, ½” Locking Hitch Pin, may be used in place of one or more of the standard Hitch Pin and Clips to prevent theft.
https://pullrite.com/sites/default/f...20Manual_0.pdf