No, it has happened to me before. See Blaire is talking AT Tia and you, if I am correct which is why Tia's message box is up(if you are understanding what I am trying to explain, it is a little hard to explain correctly). I have seen it happen a lot when going to fetch a villager for another villager. It is not a glitch though. Unless I am misunderstanding you.
this specific thing hasn't ever happened to me, however i do remember one time gayle and pippy were having a conversation and all of a sudden their dialogue switched.
i don't remember exactly what the conversation was about, but i don't know if it was a glitch that only happens once, or a programming error and this happens every time a normal and a peppy have that conversation.