So I was on a plane a couple of weeks ago and put my MBP under the seat in front of me for a bit while I went to the restroom. There must have been an exposed strut or something, because I now have a small spot on the lower edge of my system that obviously was rubbed against metal, and has a small 'burr'. What would be a good tool to remove that and smooth up that spot again (I have files, just don't really think a 'file' is the right tool)? I am in a city with an Apple store this week, so may just make a Genius bar appointment and get their recommendation, but..... Suggestions?