Apple may be cutting corners in QA in response to the lower premiums they've been able to charge over the years.
I've had hardware problems with a PBook G4 17", an iMac G5, and an older iBook. When I mentioned this to my local Apple Service guy, he told me that he's noticed that as Apple has come down in price, they've been forced to use less expensive components with correspondingly higher failure rates.
True or not, I agree with another poster who pointed out they've been much more responsive to these issues. I had all three fixed for free, even post AppleCare warranty period.
"The pyramid is opening!" "Which one?" "The one with the ever-widening hole in it!" -- The Firesign Theatre