I am running 2 virtualmin servers and I noticed recently that bind is shown as not running. Clicking to start it fails. I checked manually and bind is running and responding on nslookups on both servers. Furthermore cat /var/run/named/named.pid shows the same pid as ps -A | grep named.
In Bind settings Default PID file location(s) is set to /var/run/named/named.pid /var/run/named.pid /var/run/bind/run/named/named.pid so it includes the correct one which is the first.
I am running latest webmin 1.770 and virtualmin 4.18
Before 3-4 months I have upgraded to Debian Jessie. The detection problem might have started then or not, I can't say for sure, it's been a while since I checked the virtualmin interface.