I have two problems which I believe are closely related. First, the display portion of my laptop is loose. To clarify : there is more than an inch of "spring" to the display before it stays in its new position (much like a piece of ductile metal). Second, the latch does not consistently come down far enough to catch. I have not had luck with pressing down harder or in different spots on the lid - it catches randomly.
So, I looked more closely at the situation.
When the lid is closed (but not caught), I notice that I can move the lid back and forth on the shorter axis (not across the front of the computer, but along the side) about a centimeter. This is disconcerting. I used a jewller's screwdriver to tighten all the screws I could see, but this did not fix the problem.
Is this something that I will have to bring in to Apple to fix? I will disable the sleep-on-close, wake-on-open behavior for the moment, and sleep manually before closing the lid. Otherwise, it tends to turn on inside my bag.