My grade posting policy was set to manual. Grades were hidden. The moderation process was enabled. I did this while grading and wanted to release grades at the same time when all was done.
Lo and behold, a single student grade was posted anyway. A single one. How? Why? Who knows! Hopefully someone on here has suggestions. I'm sure I must have double clicked on something or other instead of single clicking - or something equally ridiculous - but the very fact that I could do it without realising it is indicative of very poor software design. And now I can't figure out how to undo it despite digging through these fora for hours. Another sign of poor design.
Well, I guess this student will just have their grade a week before anyone else!