check your pocket carefully! could be a fragment of something in the cotton lining? seeing as its a straight scratch!

assume this is what happened to me with my Zig Zag scratch that set this thread off!

I havnt had any additional scratches since to my relief! The one i have isnt that visable either so I'm hoping thats it for me!

If Nokia support the handset in your country have a go at getting the screen changed under warranty!