Oil Marks On My Screen

I have always regularly cleaned the screen on my late 2014 MBP, yet I failed to properly do so for a week or so. Now there is this permanent grease spot where the screen contacted the palm rest, the area looks like water residue however it can be felt when running my finger over it and it wont clean off my screen even by scratching with my fingernail or with 99% isopropyl alcohol.

This is a picture of the area and one can clearly see the mark of the touchpad where the display is not affected.