I've just done a clean of my Macbook Pro with the good old iKlean solution and while I was cleaning the back of my Macbook, around the fan exhaust, I noticed there was a really horrible smell. So (this is gonna sound weird) I gave it a sniff and GEEZ! It pongs! It's a sharp tangy smell. Like mixing vinegar with Zinc. My MBP is getting to be almost 2 years old. Is this normal? I'm a little worried now.