The smell is most likely a unique flora. Maybe that hive is your only hive to visit a particular patch of flower that affords a unique smell. Rather pleasant I am thinking. However consider butyric acid, rancid butter, which can form from degradation of many substances besides butter. This is my only concern. So, a sweet smell, is Ok, but rancid butter is cause for inspection.
A banana smell is not good, defensive alarm pheromone. My hives will present a golden rod smell this fall. I can stand downwind 50 feet and smell the golden rod.
BTW, lack of smell, is first sign of corvid19 with most, but not all folks.
Van