According to this, on a 21"-24" Samsung monitor, they do not replace unless there are 17 or more dead pixels.
Samsung Policy
I know that 1 dead pixel is irritating, especially if it's in an area that you look at quite often. You might get by and be able to bring the pixel back to life.
If your LCD screen has a stuck or dead pixel, it's usually because the liquid in the liquid crystal display (TFT LCD) has not covered that pixel fully. Try the following steps to spread the liquid and unstick the pixel:
1. Turn your computer on, but leave your monitor off.
2. Using a soft cloth, gently apply pressure to the area where the stuck pixel is. Do not apply pressure anywhere else, as this may make more stuck pixels.
3. While applying pressure to the stuck pixel, turn on your monitor.
4. Remove the pressure. In most cases, the stuck pixel will now work correctly.
This last bit was taken from Samsung's site and their suggestions to bring the stuck pixel back to life. Hope it helps.