It appears that this happens only when the image is loaded to boot up, which I did, to a 40F. The same report exists with much older version (6.0.x) but by the time it upgraded to 6.4.4, it stopped happening in that case. In my case, rebooting it once has stopped the symptom. So seems to be a bug at least with 40Fs but not sure if it could happen to 60F that has the same NP6XLITE.
But it doesn't seem to have any effects once the error stopped whatever you did to stop it. So very minor issue.