Tell that to the people on this forum who have scratches all over their iPhone 4s.
I have a 1.5 year old 3G that has two minor scratches on the screen. Not sure how they got there but they are there. Happened sometime after I removed the screen protectors.
I also have a month old 8GB 3GS that has a scratch in it's week old screen protector. Glad it was on the protector and not on the screen. This happened when I accidentally knocked the phone into the plugs sticking out of the side if my MBP.
Yeah -- scratches all over the back, sure. The front has remained unscathed. I had my 3G for 1.5 years... went naked practically the whole time. Yes, tons of scratches on the edges, back, and bezel, but absolutely nothing on the front.
I've dropped my phone countless times on cement, wood, glass, death, and disease... my screen has stayed perfectly healthy.