There's certainly a strong thread around the world of the moon having something to do with bunnies. Tecciztecatl, the Aztec moon god, is a rabbit himself, while the Chinese moon goddess Chang'e is said to hang out with a rabbit on the moon, the Hindu moon god Chandra is specifically associated with rabbits, and Artemis is the special protector of baby rabbits. Moon bunnies are a worldwide phenomenon, though they are more rare in northern Europe, where (perhaps in part thanks to Mani) we usually refer to the Man in the Moon instead. So where does the bunny mania come from?
From just looking at the moon, actually. The pattern of dark spots and craters on the face of the moon have long appeared to be a rabbit to many cultures, so much so that many of them have myths about the rabbit that lives there or the shape of the rabbit being embedded on it. To shamelessly borrow some images from others on the web, here's a picture of the moon with the bunny outlined in green:
As far as whether or not the moon rabbits hang out with one another, I would imagine it depends on where you are on "the moon" in a cosmic sense. Certainly the abodes of moony Titans like Chandra are often lousy with rabbits, but if you got into a rocketship and landed on the airless surface of the room, it's unlikely that you'd find any floppy-eared rodents hopping around. The moon bunnies are probably in a Terra Incognita - perhaps several Terrae, actually - and while you could invent some kind of moon bunny Terra paradise, the game already gives you a convenient out with the concept of the Lunar Estate boon. We would assume that various moon deities' complements of bunnies are located within the borders of their lunar estates, meaning that the moon science knows about is completely devoid of cottontails, but a sideways Psychopomp step into Chang'e's house might well bring you face to face with the famous lunar rabbit itself.
We've had Scions who visited moon gods at home in the past run into quite a few bunnies, from the general riot of rabbit life in Tecciztecatl's estate to the single, somewhat solemn bunny companion of the Chinese moon goddess. Lunar estates are separate and sovereign, so I doubt the bunnies are traveling between them much, but that doesn't really prevent there from being plenty of rabbits wherever you turn on the moon.
Or hell, invent a Terra Incognita on the moon and name it The Bunny Paradise, and fill it full of zillions of adorable rabbits who frolic in the silvery fields and cuddle visitors with their soft floppy ears. We're not the bosses of you.
