Mine had the same problem, but it had a DROP to encourage it to come loose.
I fixed it by taking the screen assembly off, removing the glass (with a putty knife and a heat gun - you can read about it on the web), removing the screen, and regluing it with some epoxy. Get the strongest epoxy you can find...
The screen is actually really easy to take off of these newer Unibody models... PowerBookmedic.com offers videos.