It's gray and I believe it's a neutral rep. I got one from her too a while back.
Grey is not neutral, it just means it's from a poster with very few posts. I forget the exact limit but you have to have xxx posts to deliver red or green. Until then both negative and positive will appear as grey.
The oldest one is definitely meant to be green, since there is no text. You can't give a red without text. The most recent one could be either.