I have air bubbles on my iphone 4s screen?

I brought a screen protector from the apple store, but i got so many bubbles in it so i took it off to try it again, but as i took it off air bubbles was left on my iphone screen [like the ones you see with a screen protector] you don't see it when you use your phone but when the back light goes off you can see it clearly, i've gone to the apple store where i got it from and they said they haven't seen this, what can i do? I'm sure they've seen it before as i looked on the internet and others have had the same problem.

IPhone screens are made of glass not plastic so unless you seriously abuse it you are never going to scratch the screen.

I have had iPhones since they first came out and never used a protector and never once have I had a scratched screen.