A couple months back, I noticed that the right palmrest of my unibody MacBook had a collection of fine scratches, like someone brushed it with steel wool (it can only be see in certain lighting conditions though). At first I thought that one of my siblings had caused the scratches by wearing a metal bracelet while borrowing my MacBook. However, more recently I've noticed that the left palmrest also now has the same type of scratches. Since I discovered the first scratches I've been careful to make sure that anyone who uses my MacBook takes off any jewelry that might scratch it so I'm sure that that's not the cause. Otherwise I can only think that maybe the moisture or occasional sweat from my hands has reacted in some way with the aluminum. Seems weird but I don't know what else to think. I didn't think aluminum would wear easily either but could that be it? Any ideas would be appreciated.