Why is Bernard’s trip of such interest to the director?

The Director is interested in Bernard's trip because it brings up a memory of a time he'd visited the reservation himself. He then relates a story of how, 25 years before, he had taken a blond Beta Minus woman to the reservation. While on an excursion, they ended up in a storm, and she disappeared. The Director shows a great deal of remorse and claims that he still dreams of the incident. At the end of the story, he realizes that he has revealed emotions that he has never forgotten. This upsets him because society forbids such displays of emotion over past events, and strong emotions are supposed to be impossible because of genetic engineering.