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:
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...