From http://www.openwall.com/lists/oss-security/2013/02/27/22 http://www.openwall.com/lists/oss-security/2013/02/27/22: By default, sudo displays a lecture

From http://www.openwall.com/lists/oss-security/2013/02/27/22 http://www.openwall.com/lists/oss-security/2013/02/27/22: By default, sudo displays a lecture when the user's time stamp file is not present. In sudo 1.6, the -k option was changed to reset the time stamp file to the epoch rather than remove it to prevent the lecture from being displayed the next time sudo was run. No special case was added for handling a time stamp file set to the epoch since the clock should never legitimately be set to that value.