IPod has a growing gray bar?

There is a gray bar growing in mid screen on my iPod touch and the pixels are dying. What I don't understand is how are the pixels dieing in a certain order... like one pixel dies and the one next to it dies (thus creating the bar) and its continuing upwards in a fashionable order. Pixels don't die in an order they randomly die. Am I right? If you know how to fix this or what is causing this i'm all ears.