Just now I was posting an add on Gumtree trying to sell my iMac, then I went into Dashboard to look at some notes and noticed some black indent- like text, from the Gumtree add. Is this screen burn? I had a quick search on Google and found out that this happens more in cold environments. My room is very cold at the moment, but I haven't had anything like this happen before. So, is this something that Apple can fix if I send the iMac in? It's still under AppleCare. Any help would be appreciated, thanks.