It's not that uncommon. When a beehive is doing really well, it'll "split", meaning they'll raise a second queen and the new queen will leave and half of the colony will go with her to establish a new hive somewhere. This is called swarming, and it's the their version of reproduction. (Tangent: Contrary to popular belief, honey bee swarms are usually very docile since they don't yet have a home to defend.) Once they find a suitable location to settle, they'll move in. Without humans building things, a suitable location would usually be something like an old hollowed out tree. But humans build great beehive homes. Old houses with small openings between siding panels that allow bees into the walls are a common favorite.