Since Feb 13th, cron has been sending messages like the following from invocations of wmf-auto-restart on db1106 and db2085:
Cron <root@db2085> /usr/local/sbin/wmf-auto-restart -s ssh --- Showing one /org/freedesktop/systemd1/unit/ssh_2eservice Sent message type=method_call sender=n/a destination=org.freedesktop.systemd1 object=/org/freedesktop/systemd1/unit/ssh_2eservice interface=org.freedesktop.DBus.Properties member=GetAll cookie=1 reply_cookie=0 error=n/a Got message type=method_return sender=n/a destination=n/a object=n/a interface=n/a member=n/a cookie=1 reply_cookie=1 error=n/a
It appears a kernel update was applied on those servers that aren't on any other database:
Start-Date: 2019-02-13 07:51:49 Commandline: apt-get install linux-image-amd64 Requested-By: jmm (11984) Install: linux-image-amd64:amd64 (4.9+80+deb9u6), linux-image-4.9.0-8-amd64:amd64 (4.9.130-2, automatic) End-Date: 2019-02-13 07:52:05
The main difference I could find is the affected servers are running the newer kernel 4.9.130-2.