Sorry for your loss of a sweet bird. I lost one of mine when the weather first turned cold and after a nasty rain storm. I believe if they get chilled to much they shut down inside. He was a wonderful and large brownred named Pita. This weather is just harder on birds originally tropical.
I'm so sorry for your loss. He was an adorable little guy, and it sounds like he had a very happy life with you. I lost my black Japanese bantam rooster in November after having him for more than ten years, so I know the feeling of losing a rooster who was truly part of the family. It's very sad, and so strange for them not to be there when you go out and visit your flock.
Just remember that you gave him a good and happy life, and in the end that's really all a chicken (or anyone) can hope for.