Maybe a minor bug and not sure if/how this can best be dealt with.
I just moved a handful of whispers to another topic, and it generated the “SPLIT THIS TOPIC x MINS AGO” message visible to the public. Oops. It seems to me the public should not see that this split took place because the replies were all whispers. But I can imagine it might be overkill/not worth the effort to write code to parse out which replies are whispers and which are not, and to generate separate messages.