Found it:
The former president was telling a group once about his tumultuous days as governor of California during the rebellious sixties and early 70s. He said he had a meeting with some of the organizers of the protests. They came into his office wearing t-shirts and jeans, and some were barefoot.
Their spokesman began, "Governor, it's impossible for your generation to understand us.... You didn't grow up in a world of instant electronic communications, of cybernetics, of men computing in seconds what once took months, even years, or jet travel, nuclear power, and journeys into space...."
When the young man finished, Reagan said, "You're absolutely right. Our generation didn't have those things when we were growing up. We invented them."