The man pointed out something unique about the coffee mug. It had some special feature or something.
The man smiled, but his eyes were sad. It reminded me that one of the nicest things we can do for others, oddly enough, is to let them do something for us. The man at the booth probably wouldn't have minded if the woman had taken the mug home and given it to charity or tossed the darned thing in the trash. He wanted an acknowledgement that their conversation had been meaningful and that his gift had merit. The woman, who was quite kind, had taken a utilitarian view of the offer.
The man, however, saw it as much more.