Repeating Error Xsan v3

I'm seeing the following error on both MDC's periodically during the day.

6/18/15 10:35:43.626 AM Xsan Admin[5890]: ERROR: No authenticated licensable computers! returning nil

This message will appear and repeat up to 30 or more times, then disappear for a time, only to return again.

The volume is up and running, staff is working, controllers and clients are behaving normally otherwise.

Anyone have any insight as to what it means?