As it was mentioned the break-in in differential related, and nothing else.
I also beleive the Ram manual says not to exceed 50 for the first 500 miles of towing. That's a limit I would stay closer to if you hook up at 501 miles, but if you don't tow for the first 5,000 or 10,000 or more miles I wouldn't worry about it too much.
If you tow at the 501 mile mark and the trailer is heavy I would plan a few extra rest stops that are a little longer than normal to let the diff cool, that is if your going more than 100-150 miles.
