I've just received a replacement iPad Air, after waiting a month and a half for stock to come in, so imagine the sorrow and anger I felt when I noticed the screen had two black marks on it! This is the third btw; first book spine shadow, second dead pixel... I've never seen this before, and I'm not sure what exactly they are; both are a faint greyish black, one is a wispy line shape, the other more dot/splodge shaped. What I can say, is that they're certainly not dead pixels, maybe they are dirt, or possible damage to the substrate. What I can also add, is that the screen suffers from the well publicised 'book spine' effect, in that the lefthand edge has a dim shadow-like effect; the righthand side is fine of cause. I've decided I've had it, I don't want to do this anymore, I've asked for a refund!