The document [name here] is on a volume that does not support permanent version storage

I am running Pages v8.2 on a Macbook Air with OS 10.14.6 Mojave. I am working with multiple Pages documents stored locally on the internal hard drive and not residing on any cloud server. One, and only one, of these documents is suddenly, as of today, giving me this message about "permanent version storage" when I attempt to close it; multiple other recent Pages documents, created at about the same time and stored in the same folder on the same internal hard drive, do not show this message upon closing. All these documents contain tables, if that's somehow relevant.

Am I in danger of losing this document if I go ahead and close it? Why is this only happening to a single document? Is it corrupted somehow, should I try to create a copy of it? What do I do here?

ETA: I copied the document and created a second version of it, and saved that and closed it without receiving that message. I then went ahead and closed the original, reopened it and saw that it appeared complete and unchanged, and re-closed it and didn't get that message. Sunspots? Gremlins? Because Apple?...