IPod touch 4G screen "static"?

Every once in a while (about once or twice a day) certain icons and ons on the iPod touch will turn to "static" for a brief second then go back to normal. By static I mean the icon dissapears and is replaced by horizontal lines that kind of flash (disappearing and reappearing lines) and have colors like pink and purple. Is there anything wrong with the iPod or is this normal?