Q: Removing non-sticky residue from Macbook pro screen

I cleaned my MacBook pro today, and had a small square placed over the camera that I cut from a regular post-it note. It was on there for several months straight. It came off no problem but left a little residue, which I didn’t see has a big deal since I had done this before and the residue came off no problem in the past. So I began to wipe my screen as I always had. When I finished I noticed that there was a longitudinal smudge across the top of the screen where the camera is. Now, the residue is not sticky or rough in anyway (kind of like when you remove a sticker, its not like that at all). It is smooth and it feels just like the regular screen, but you can clearly see the smudge. I have tried everything I could get my hands on, water (that’s the only thing I’ve ever used on my computer), Windex, oil, and lighter fluid. And I make it worse with each attempt to remove it.

Has anyone else ever had this problem, if so how did you fix it? Please help it really bothers me.