Just put up a screen that is entirely white, and then another one that is entirely black. If there's a dead pixel, it will show up as black or colored on a white screen. A stuck pixel will show up as colored on a black screen. Hopefully you haven't gone 0-2 on your first day with a MacBook Air. If there's a dead pixel, just bring it back. I have yet to see a software fix work, and once you notice it, you can't "un-notice" it. Just make sure it isn't something on the screen (a drop of liquid can look like a stuck pixel since it magnifies the pixel).