Possibly. Not likely, though, Because it has happened more than once, I watch for multiple instances of Suricata.
The issue has not arisen since i posted the request.
I had changed a backup script and caused a lot of network traffic for a long time. Occasionally the remote host loses its mind and needs booting. So did that, and booted the Suricata host as well.
Since then, no problem with data transfer, not even the large backup that took 30 hours to complete. (I am looking into that; the backup should have proceeded much faster.)