My new Retina iMac had a plastic film protector stuck to the screen when I first took it out of the box. When I peeled it off, it left a sticky residue. For the first week I didn't mess with it. Later, when I tried to remove a big thumb print that I noticed, it smeared the oily residue (oily residue from the display not the thumb)everywhere I rubbed. Multiple attempts to clean it with water and a microfiber cloth just seem to smear it around more. Obviously trying to remove the oily substance with just water doesn't work and using any kind of detergent is out of the question. Is this supposed to be there? Is this normal? Suggestions on how to remove it..