Hibernating angels
We often say that in certain dangerous situations, from which they miraculously escaped, people have an angel on their shoulder.
As a Christian, I believe that there is indeed angels are who can support people in all kinds of situations. There are also angels that can take on human forms. They take action at the behest of God and do nothing of their own accord. It's not those cute angels with wings that you often see at Christmas.
The angels in this story are just not in the mood to work in the cold winter months. Why do we have to go back to Earth anyway? It's so cold there and here in heaven, by God, it's nice and warm. We want to enjoy His warmth and we will come back in the spring. We're just going to hibernate; goodbye.