Chalked brood in new split


I just split my strong top bar hive one week. I moved three frames of brood and bees to the split. After several days, I noticed a lot of white and dark chalked brood under one of the frames in the new hive. Since they were dry and hard, should I assume the capped brood had died over winter in the existing hive and the new split bees started to clean out the frame or could they have gotten cold and died in the new split?