So the other day I did my final inspection and started preparing the hive for winter. A few minutes after I had finished I noticed I put my feeder rim on upside down. I re opened the hive and saw that the bees had clustered on the inner cover..looked almost like a swarm cluster, bees clinging to each other etc.. I knocked them down (gently) and re checked again a day or two later. Still had a cluster but this time it was a baseball sized cluster. Can any one tell me what this behavior is? I am a first year beekeeper up in Maine..