Yes I have seen this bees will not leave brood and bees also do not like to disconnect from the food neither. When did the hive die, late fall, and the bees were protecting the last of the fall brood. Or in the spring and the bees were covering first of the new brood in spring? Was there a band of honey along the top bars of the bottom super? It could be possible that you suffered 2 separate die offs. The first being the bees remaining on the small patch of late laid brood and the weather got cold enough for the bees covering the brood to contract away from their stores and starve. The 2nd when the hive didn't have enough bees left to keep the hive warm enough and then also ran out of food that was available to the cluster. Bees need empty comb to cluster in so over feeding can be detrimental to a hive. if the bees are forced to look after a small patch of brood in the top supper but the empty cells are in the lower super for the bees to form the winter cluster, you could cause the cluster to split during the first cold spell. I have probably added more questions than I answered, Sorry.