Some of my villagers do that whenever I need to deliver presents. I found it really weird at first but then accepted it. Uchis and snooties seem to do that the most for me.
That happened in my town too, especially with my uchi and peppy villager. It seems to be a translation or programming error with the localications, I guess.
Mine don't do it so much about each other as they do about my friend's one character. I've had multiple of them tell me they either met Mila or remember Mila from when they lived in my friend's town and they always say HE seems like a real bell pincher, or HE did a good job designing their shirts or whatever. And ALL the villagers I've gotten from that town from her do it, but she definitely set Mila up as a female character. I was actually thinking about it earlier today, it's so weird.