Plasmas have a small falloff in phosphor output after the first 100 or so hours of use. This is also why they are more susceptible to burn for the first 100 hours. They then settle at a level where they then degrade very slowly for the remainder their working life. The level at which the output falls during that first 100 hours is variable and may not be the same for red, green or blue, so it is best calibrate it after this period as you can end up with very slight white balance changes. 99% of users would probably not notice this but if you want it to be spot on, it is best to wait.
