No ... it's complaining about the perms on the crontab file,
not on any entry cron points at.
ls -l /etc/crontab
And as for the job; look at the time-stamp, compare against
all the possible cron jobs on the system. If there are no
individual ones per user, it HAS to be a job in /etc/crontab,
/etc/cron.d (.hourly) (.daily) (.weekly).