Hello Pixelguff,
The nokia 5510 are refurbished display, that's why some of them might have scratches. As they say on
adafruit's page, "These screens are recycled from older cell phones so they often have tiny nicks or scratches. There's no such thing as a 'new' Nokia 5110 display, but the scratches are not noticeable when in use. "
When I assemble and test Gamebuinos, I put away the ones with big dents or to much scratches. I might have missed yours, I'm sorry about that. If the dent is really embarassing, I can send you a replacement screen. But for now you'll have to wait about one month, as I keep displays for Gamebuinos being assembled (I don't have extra stock yet). If you can't wait, you can always buy one for cheap on eBay.