My Nexus 7 (C70) suffered badly with screen lift, with it making irritating creaking noises when I touched the left side of the screen (when viewed in portrait). I previously tried the "tightening screws" fix, only to find all the screws were tight. Now I think I have solved the problem...
On looking inside the case again, I noticed the left hand side fixing screws were not mounting the screen bezel onto the solid metal chassis (as with the right hand side fixings), but only to plastic components, which would move about if pushed. I believe this is the design flaw that leads to the screen assembly detaching from the bezel. The adhesive between the bezel and the screen gives up because the bezel is being pulled away from straight by the fixings to the plastic components, which don't provide a decent, straight and rigid chassis.
I have now removed the three fixing screws from the left hand side and pushed the screen-bezel adhesive back together. Now I have no screen lift or creaking!
I have read of people finding screws missing when they open their Nexus 7. This is possibly Asus attempting to fix the problem in this way themselves if it becomes evident during factory QA.
I'm not concerned about having screws missing. The screen bezel is firmly held in place by the back cover. It is the internal fixings which are constantly trying to pull the bezel away from the screen, while the screen is trying to remain flat, which causes the adhesive between screen and bezel to give up.
Update... spoke too soon, the adhesive has given up again. I'll resort to using a case now.