Hi guys. I was cleaning my MBP 17 today and came across these. The white part were more brownish, some had the oily rainbow color, etc. But the thing is Im not sure if these are like this or its a corrosion. I dont recall spilling anything on my MBP throughout the middle of the body. tried cleaning them with isopropyl alcohol with qtip but it didnt come off (Im guessing its not a corrosion then?) Here are some of the pics. They seem to happen only around the screws. Thanks in advance.