Yep. It's normally pretty reliable. I'll let you know if the problem repeats. It was pretty weird seeing the interface showing a post scheduled for "9 minutes ago", or something like that.
; -)

Also, it seems that when I did "revert to draft", the post lost its community tag. It also lost all beneficiary settings and the custom author under "Advanced Settings". I knew about the last two, and fixed them before posting manually, but unfortunately I didn't notice that the community tag was gone.