Wierd 'ps ax' output

[Jonathan Matthews <jaycee@jaycee.uklinux.net>]

Can anyone help me work out what this entry in the
process list is:


  PID TTY      STAT   TIME COMMAND
[snip]
  186 ?        S      0:00 /usr/sbin/cron
[snip]
16891 ?        S      0:00 /USR/SBIN/CRON
16892 ?        S      0:00 /bin/sh -c   if [ -x /usr/sbin/exim -a -f /etc/exim/exim.conf ]; then /usr/sbin/exim -q ; fi
16893 ?        S      0:00 /usr/sbin/exim -q
18318 ?        S      0:00 /usr/sbin/exim -q
18319 ?        S      0:00 /usr/sbin/exim -q
18320 ?        S      0:00 /usr/bin/procmail
18321 ?        S      0:00 /usr/sbin/exim -q

I'm fine with #186, but why have I got #16891 there?
According to pstree, it's the parent of the subsequent exim and
procmail processes, but there's nothing in my /etc/crontab to
suggest that anything should be going on around now.

Does this smell fishy to anyone, or am I getting needlessly
worried?

ta,
jc