The link here indicates a more systemic problem:
Windsor explained that the screen of the iPhone uses a chemical deposition to provide touch sensitivity based on heat. The international property rights for this technology, he said, were purchased from a bankrupt Finnish company that was trying to make a similar device. But that company encountered the problem that with extensive use, the film would begin to degrade and the screen would lose its sensitivity. Windsor said the problem typically manifested itself within three to six months. While Apple should have been aware and fixed the problem, the broker said, only time will confirm that all is well with that touch screen. (link)
http://blogs.business2.com/apple/2007/08/iphone-dead-zon.html
Interesting if true - I’m somewhat skeptical since I believe one of the “big boys” ( Sharp? ) was the original provider of the screens. It would not make sense for Apple to develop or purchase it’s own untested technology when it could pretty much buy everything off the shelf.
But who knows ? The iphone discussion boards bring out new problems every few days it seems.