Isaac and Ari went to camp. I mailed them cards before they left because it takes a while for them to reach the camp. I received a card from Isaac from Canada, not long after he left. When they returned, I spoke with both and thanked Isaac for the card. I told Ari I was aware he had sent his aunt a card. He said that he did not have time to write this year and reminded me there was one year when he sent no one a card.
I choose to let this pass.