Drones in Fall ?

Bee Colonies have a reason for the things they do.  My role as beekeeper is to try to figure out when something is wrong that may threaten the viability of the colony. Drones (male bees) are kicked out of the hive in fall.  When I see one hive that is keeping drones when the others have evicted their males, I worry that this might be a sign of trouble even though things look ok.  It's a puzzle !  The bee in front is a worker..the bigger eyed drone is just behind.