depends on how tight the people at the Apple Center are. Some people have had ACDs replaced with just one dead pixel, others have stuggled to get it replaced with 5.
If it's really obvious, and you can honestly say it distracts your workflow, they may be lenient enough to replace it for you. I know i would be pretty cut if i forked a few Gs over for a display with glowing green dots everywhere.
Arent there any standard numbers of burned pixels that each company takes replacement procedures over sutch displays? I wqs once told that if its over 3 then u certainly get a replacement. I cant remeber by which company though!
Do a Google seasrch for ISO 13406-2. This is the standard that all manufacturers should have to adhere to. Unless the product is "Class 1" there can be a certain amount of faulty pixels before they will replace them.