It must have been toasty in this soffit since the bees were "bearding" around the cavity. This is normal behavior every beekeeper sees outside their hive. Typically this occurs when most of the foragers are back from a day's work and need to make space for the continual feeding of the larvae by the nurse bees. They also beard in order to keep the temperature of the hive manageable as well as to help regulate carbon dioxide levels inside the hive.