I suspect if you take 2 or more phones to an Apple store exhibiting this problem, you'll have a much better chance of getting something done about it than you would with one. Even without any warranty left. If you do have warranty or AppleCare, then definitely take them back.

I thought I'd read something about free loaners recently (this year) but a quick google only turned up something about a $30 loaner from back in 2007. Worth a call to Apple Care at least.