I'm with you. I think the previous owner saw the delam and sealed it up real good after the fact. As long as everything is sealed good, you shouldn't have to worry about further damage. Repairing water damaged delamination is very expensive if done properly, so I wouldn't bother on an 05 trailer unless it really bothers you. The chalk on the rubber roof is normal oxidation from the sun and weather, but after you wash it, treat it. It can benefit from some sunscreen as much as anything. I highly recommend a good thick coating of this stuff once a year.
