My 4yo asked me why I go to work
I told him I go to work so our family has a home and food and can do fun things together. He thought about it and said 'you're a good dad for doing that.' Didn't expect that kind of validation from a preschooler but I'll take it. That's staying with me forever.
This hits different when they're that age. They really do absorb what you're saying even when you don't think they're listening. Did he ask any follow up questions?