I honestly do not know what you're talking about.
I have the 1Ghz system and the LCD is as stiff as a board. No warping or flexing whatsoever.
I think that if your system is flexing like that you should call Apple and have them bring it in. At least call them and make a case number about it.
Let me mention something: I had a 550Mhz system (Titanium Powerbook) and when it arrived the hinges were VERY stiff. I called and made a note about it with Apple and logged the case number. (Because we have a LOT of systems we keep a notebook for each and every Mac and when it has a problem we write down the date, the issue, the time we called, who we spoke to, and the case number that is given so that we can keep track of that particular system.)
Well, about 10 days later my wife is opening the system up and "Crack!" The right hinge snaps completely.
We called Apple and they brought the system in for repair. Apple actually swapped the system out completely with an upgraded 667Mhz Combo system (this was 550Mhz DVD drive), but the interesting thing is that the Apple Customer Relations person dealing with our case said, "One thing we noted was that you had alerted us to a stiff hinge so we realize that this wasn't negligence on your behalf."
That taught me/us an important lesson: Even if something seems very minor, it's a good thing to call Apple and let them know because it could have more serious ramifications down the line.
So, even if you can live with the issue, it's a good idea to let Apple know what's going on.
Good luck!