I have heard of the screen scratching many many times on all the different forums that I read on. The screen doesn't seem to be as tough as the one video shows where the guy used keys on it.
Not sure there is an easy answer to this as to why or how to prevent it. I have been using an iSkin Revo case that has a plastic piece that protects the screen and I have no scratches on my screen.
I'd purchase the Power Support Crystal film. Feels like glass but it isn't . Who knows, it might cover the little scratches underneath and render them invisible. But as others have said, contact Apple first, as my iPhone's screen didn't get scratched after a few days usage, and I used the cover a few days afterwards.