IPod touch screen doing somethig weird?

When i turn on my iPod, it fizzes out/turns into a black/white/blue lined screen that has the time onthe bottom of the screen. It only stays there for a second though then it goes back to my "slide to unlock" screen. My iPod works fine except for this one problem. What's wrong with my iPod and how do i fix it? I have never dropped it, or damaged it.