On the upper left side (where the charger port is) of my Macbook Air, the aluminum is chipping off of my laptop. It is not a matte silver, but a shiny color, like a knife. I don't abuse the computer at all. However, I do carry it around in my backpack a lot for college. I keep it wrapped in a plastic bag (in case it rains), so it is rubbing and bouncing against that all the time. Could that be causing it? Is this normal? The rest of the computer looks fine to me. There are zero performance issues with the computer. Thank you for your time.