why won't my timestamp timeout in sudoers work?

Wanting to decrease the frequency of how often I have to enter my user password to sudo, I learned how to change the time interval. I found out that I have to addCode:, timestamp_timeout=60 to the end of the defaults line. So, now the line in my sudoers says: Code:Defaults env_reset, timestamp_timeout=[time]The next time I used sudo a few minutes later, I had to enter the password again. Why would that be? Do I need to restart for the new time interval to kick in?