Raelreal -
If it gives you any reassurance, I once had a Hassy Superwide that had a physical scratch on the rear surface of the rear element, actually in to the glass, not just the coating. It was near the edge of the element, but nonetheless. I was concerned about it, as I knew about the scratch when I bought the camera (at a considerable discount). To test it, I went outside, pointed the camera directly into the sun and shot away. It had NO impact on the images whatever, even with direct sun into the lens, even shooting wide open. I wouldn't worry about a little wear on the coatings on an interior element.