I would try using some compressed air from below it in the battery compartment. Don't have the machine on and certainly don't hold the comp. air at an angle so you don't freeze something.
Either way, if it's a real problem, and you can confirm it is (for example, have your friend's macbook and yours out and have someone else see if they can feel the difference), then don't hesitate to make an appointment at an Apple store and head on in. If nothing else, bring in your friend and his macbook in so the genius can feel what you are talking about, and even offer to test it out next to a similar display (they should still have white ones in there).
Then, explain that you know it's not a huge deal, but (maybe) it doesn't click sometimes or makes double clicks not always work, and explain that you would feel better or whatever and would like to get it fixed. The top case for a macbook is the entire keyboard/trackpad section and isn't all that difficult or restrictive (because it has multiple areas that can fail, such as each key, trackpad, clicker) for them to replace, though could easily take them a few days depending on work load and whether or not they have to order that part (I imagine at this point they would) in which they would need to have your machine in.
Hope this helps.
