Aged green coffee changes color naturally, from a deeper green immediately after harvesting, to a lighter green (grey), to a lighter yellow.
Aged green coffee can safely sit for years without any negative effects, as long as it is stored in a relatively dry, cool, and dark environment.
Your coffee is absolutely still good for roasting and is actually preferred, by me and many others, over new crop unaged green coffee.
More on Quora thread.
