I'm probably gonna get hammered by the weight police, but...I tow a Grand Design Momentum 328M with my '15 2500HD and recently felt a pretty hard bucking when hitting the brakes. Had no toys in and fuel tank was almost empty. Brakes feel just fine on the truck when not towing so don't feel as though the rotors are warped. Controller set at 6.5. Someone mentioned possible grease on trailer brakes? Any ideas?