Got this problem as well. Called on the guarantee, they will send it back to Nokia and I'll recieve a new N9 today.

It was really annoying to see a clear black stripe while the area around was covered with finger prints.
The scratch couldnt get smudged (just stays clear black), that's why you see the scratch everytime while using the N9.

Salesperson told me Nokia still could refuse the guarantee if they dont see any problems with it. He told me that 2 others also complained about this problem.

Had my N9 about 30min and then I noticed the scratches. Nothing was in touch with the screen except my fingers. And I'm not Edward Scissorhands :P

@smegheadz:
It really looks like scratches. Also thought the scratch could be on the underside.