A line of people has formed to enter a place where only members are allowed inside. There is a doorman who says something to each person, and based on the person's response he can determine if they are a member or not. A former member who recently returned from a 10 year prison sentence approaches the entrance. The doorman, who happens to be a Star Wars fan, playfully takes advantage of the current date and says, "May the 4th be with you." The former member says something in response, and the doorman then says, "You are no longer a member. You may not enter."
What was the former member's response, and how did the doorman know the person was no longer a member?