As you ran your finger across the screen, did you notice the change on the screen? You probably damaged the screen. If you can convince Sony that it's a factory defect and not intentional damage, go for it.
Two months ago I bought a Sony LCD monitor - my first. While indicating something on the screen to my wife, I ran my finger across it several times. This left long lines which look like scratches all across the screen. They have not gone away. Is this normal, or should I return the monitor under warranty?