I Just received my Sigma 30mm f2.8 that I bought on Ebay last week. It was listed as new in package, and did indeed come packaged as new. When I opened it up to inspect it, I found what looks like a small scratch or flaw on the interior side of the rear lens. Its not very large, but it is noticeable. I was wondering how I should proceed. This is my first step into a camera system, so I don't have any real experience with interchangeable lenses. I also don't have a lot of experience with Ebay, so I want to try to figure out the best way to handle this. I know that there is a warranty from Sigma, but in the warranty it states that in order to qualify for that you had to purchase it from an authorized Sigma seller in the US, which the seller from Ebay more than likely isn't. I was planning to contact the seller after work today, but should I ask where and when he first purchased it, or go another route with him? Or is a lens flaw more common than I think? Will it even effect the pictures, or be noticeable in the pictures? Here is the best picture of it I could get. Like I said, I just want to handle this the best way possible, so I would appreciate any advice anyone has to offer. Thanks.