I have the same issue on the upper inner edge of my driver's side headlamp assembly - 2004 4.4 X5. It was just in the body shop for unrelated front end damage and they would not repair/replace the headlamp assembly under CPO - it was undamaged in the wreck. My SA said it was normal aging and quoted me a price of $1100.00 +/- for a new one. I'll just wait to hit another deer and aim left this time.