I could be just the location of one hive draws the more drones for one reason of another. Drone traffic is by no means a indicator or much. At most it might mean a queen replacement or some type in the vacinity. That hive or one near it. Drone traffic isn't even a good indicator of a failing queen (drone layer) or laying workers this time of year in the northern hemisphere. But it is always worth a check to allay your worries.