WAY back in 1975 my husband and I were on our honeymoon in Acapulco. We were on a tour bus and some ahole was talking on a "new cel phone." I got annoyed at him because he was talking while others were trying to listen to the guide.
It was rude then and it still is.
Your 25 year old son was being rude. He knew it and it showed how important YOU were. :o) Maybe the text was from a VERY hot female. You remember that, 50ish or not.
This particular son is a complete loner. I'm sure it wasn't a hot female. Fortunately he is straight.