I'm stumped. Looks to me like a manufacturing defect that you might have to live with. A few cedar wedges and the judicious use of a hammer, with a piece of 2x4 to spread the impact, might spring the door up just enough to let it close a bit more easily. Follow that with some silicone spray. Might be worth a try.
Happy Camping! ///// Richard D.
2006 4x4 Ford 250 SD / 2007 Flagstaff 827 FLS
One very patient wife and one furry child who travels with us. Forty-two years of trailering and camping, and I still have a blast.