I have three little horizontal 'tears' in my screen as well. I've never handled mine rough or dropped it an it's been in a case/cover since I got it as a gift this past Christmas. The last tear appeared when I had put it down for a few second to answer the phone, when I picked it back up there it was. The first two are in a horizontal line with each other in the middle of the screen and the other one lower and off to the left. The surface of the screen is blemish-less and if you know where the tears appear when the back-light is on, you can just barely see them otherwise it looks like they are below whatever layer the type is on and above the light emitting layer. They look like someone took a paring knife and poke them through, though why the layer would tear like this I have no idea.
Called 800-THE-BOOK which is their support line and they are going to send me a replacement under warranty. We'll see if that holds up better.