I know Brit troops dyed their stuff or wore temperate kit. I'm SURE US soldiers have done the same from time to time. Which is why at first that's what I thought this was. But this is different. The plastic bits on it are a true green, whereas the production stuff is almost a true gray (it does have a hint of green to it IMHO). I'll take a pic or two of the pieces next to each other and post them here. There's no chance they are the same stuff.
So if the plastic bits are green, and the plastic bits have to be sewn on during manufacturing (not after, based on how the stitching is), it's pretty certain this thing was made to be green from the start. And if that's the case, it probably was overdyed when in raw cloth form and manufactured from there.