I have recently noticed that my MacBook does not sit evenly when the screen is open...the bottom-right corner is slightly elevated. When you close the lid even 3/4 of the way, it drops back onto the table. It's not just my table this is happening on, I've seen it on 2 or 3 tables now. Here are a couple photos showing what I mean. The first is with the screen completely open, the second is with the screen 3/4 closed. Any ideas what is causing this, or how I can fix it?