What you saw in the sudden friendliness of your oldest son is the fulfillment of a bible text. Proverbs 16 v 7 says: " When a man's ways are pleasing to the Lord, he maken even his enemies live at peace with him".
This glad happening with this boy of yours says to you. "For the moment you are in a good track with the Lord".
Why do I say: ' "for the moment".
Sometimes it is so, that we are slackening with our way with the Lord. We get distracted or forgetable, a danger threatening us all.
Go on with this good way, Yeaux-yeaux. The Lord showed you one of his treasures. There are millions of treasures more.
Mind Yeaux; I never promised you a rose-garden. No roses without thorns. Hold on, when there is such a thorn. Your future is glory ...with the Lord.