Sometimes if you are mailed of cronjobs, will may got an error like this:
/etc/cron.daily/logrotate:
error: error running shared postrotate script for '/var/log/mysql.log /var/log/mysql/mysql.log /var/log/mysql/mysql-slow.log /var/log/mysql/error.log '
run-parts: /etc/cron.daily/logrotate exited with return code 1
Well, don't panic! Also don't ignore it! :)