OS X :: Dot Mark And Tiny Horizontal Line On Screen

I've just noticed two small marks in the lower right-hand corner of my iMac's screen: a tiny horizontal line to the right of a dot. I can see them when I restart the computer, but not when the wallpaper is on the screen. Clear Screen won't remove them, but they don't seem to be scratches either, partly because I can't feel them. Do you think they're dust specks or something like them tat somehow got behind the screen? I hope there's a safe way to remove them because I hate to see them.