Literally just bought the new 2017 mbp w/ touchbar a few days ago and I saw this in the light today. Tried to clean it and it's not coming off... This is taken with my iphone flash on. It isn't really visible in normal light unless trying to look... Haven't dropped or damaged my laptop in anyway and have been taking care of it (in a case and all). What is this.. and is it a big deal? Should I return it ?? It's only really visible in light..