I think he is referring to the greenish tint from his LED lamp, not trying to actually change the color of the LEDs.
Grendals is on to it...check your lamp, it likely has a lens covering/protecting the LEDs, the lens itself may actually have have the greenish tinge to it, and not actually the LEDs. The lense may have a thin protective film on it as well that you can peel off, sometimes they ship them with this film on it, to protect the actual lens from scratches during shipping. Couple of things to check anyway.