Oddly enough I just did just that. We were at the beach, and the sky just opened up. Everyone ran to the shelter/change rooms. They are situated at the top of a sand dune. There is an access/maintenance road up the back of the dune that is about 400 feel long and fairly steep.
So, I ran to our Routan, and drove to the access road, but as it is a narrow road and I couldn't recall if there was room to turn around at the top, I decided to back up the hill to gather everyone up.
Anyway... it went up the hill in reverse like a champ, no complaining, no shaking, no grinding. I even remember thinking "Hmmm... that went well."
So I would say it shouldn't do that. Take it to the dealer for warranty.