Nagios sending a warning not found in my logs

I've installed Nagios on my Sun System 3 months ago. Everything is
working fine. But yesterday i received a warning message from nagios.
Nagios check the /var/adm/messages to send these. when i look in the
messages log, i found no warning at all??? Can this be a problem???
How can i receive a "warning" from nagios if there were no warnings
detected by my server?

The command in my nrpe.cfg file is like this:
command[check_msg]=/usr/local/nagios/libexec/check_log -F
/var/adm/messages -O /usr/local/nagios/check_log.warning -q "WARNING"

thanks for the help!

jimmy