I've noticed on my unibody that there are some black spots on the unibody near the keyboard as well as some areas on the edge of my keyboard. I'm getting my unibody replaced for a separate reason but I was wondering if I could know A.) what these are and B.) is there anyway to prevent them? Is it just a matter of regularly wiping it down after use? Not putting down my hands too much on the palm rest? Image (taken via my cellphone) is at the link below. http://i.imgur.com/Uq3jl.jpg Thanks.