The lesson from the story is not to act out of anger. We also talked about how the hawk was acting to protect Kahn even when Khan thought he was being irritating, just like sometimes parents and other adults tell kids not to do something to keep them safe.
The same night we read this story was Caleb's turn to pray at dinner. He says (among other things), "Help us to listen to other people and don't kill birds."
Understanding from a 4 year old?
I think so.