Hi rs --
If you feel like doing it yourself, you could try using the
Al Glide hinge adjuster kit from Radtech.
But, since you're covered by AppleCare, you might just want to avail yourself of that and have Apple fix the hinge for you professionally and for no added cost.
I'm not sure whether you could get this type of maintenance done on site, either at a Genius Bar or at an AASP, but it might be worth looking into to see if you could since it's not too complex an undertaking. That way, you would have to part with your PB while it gets fixed.
Good luck.
-- JDee