This is exactly my thought as well. To me, the days of the week and month names are colored as well, but I wonder if we just used colored signs and posters to learn them in kindergarten
I explicitly remember looking at the colored letters of the alphabet in my first grade classroom that kind of wrapped around the top of the room and thinking some of them were wrong. There was another set of colored letters in kindergarten near the chalk board that I can’t remember explicitly, but I think it was “right”, or at least more right.