ssh-based FreeBSD monitor not alerting when sshd daemon dies

We've setup several FreeBSD machines to be monitored using ssh logins. As a test, when we shutdown the sshd daemon on one of those machines, the monitor for that machine did not send out any alert indicating that the machine was "offline". The monitor simply stopped polling. The poll cycle was set at 1 minute, and we waited in vain for 30 minutes for an alert to be sent. Or even an indication that there was a problem. The monitor show the FreeBSD system as "green" the entire time.

The only indication we had of anything being wrong was when I refreshed my browser on the particular monitor (Monitors > FreeBSD > 10.10.10.51 ), I saw a message at the top of the screen:

Unable to connect to Connection refused: connect