Permanent "fingerprint"?

Hi,

I have a 10 month old iPhone 4S and the other day I noticed a really big smudge/fingerprint on the screen. The smudge is only visible when the screen is off, I tried to clean it with no luck and it´s getting really annoying...

I´m going to an Apple Store next week (here in Spain there aren´t many) to see if they can replace it.

What do you guys think?

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