Jonathan Hanks pointed me to this fix to the gpstime kernel module that was unfortunately put in after the 3.4 release that we're currently using:

https://git.ligo.org/cds/advligorts/-/commit/6f6d6e2eb1d3355d0cbfe9fe31ea3b59af1e7348

I hacked the source in place (/usr/src/gpstime-3.4/drv/gpstime/gpstime.c) to get the fix, and then rebuilt the kernel module with dkms :

sudo dkms uninstall gpstime/3.4
sudo dkms install gpstime/3.4

I then stopped daqd_dc, unloaded gpstime, reloaded it, restarted daqd_dc.  The messages are no longer showing up in /var/log/messages, so I think we're ok for the moment.

NOTE: the fix will be undone if we for some reason reinstall the advligorts-gpstime-dkms package.  There shouldn't be a need to do that, but we should be aware.  I'm discussing with Jonathan if we want to try to push out a new debian package to fix this issue...