This is a manufacturing defect. I find it annoying as hell, but yes it is fairly common. Companies such as Dell actually have standing policies not to allow warranty replacement for an LCD screen unless there are 5 or more dead pixels clustered within a 1 inch area of the screen.
Damn, remind me never to buy a LCD monitor from companies such as Dell. If that policy is not listed on their website and they refuse to replace the monitor.. I would take action. The Better Business Bureau has helped significantly with several issues I had over the past few years. A manufacturing defect is a manufacturing defect...