First, you did not see ghosts!
The effect is happening right now as well (for me, for example).
Explanation is most likely as follows:
There are actually 2 of each server, so Stef can switch between them in case one needs to be serviced. That happened yesterday and today with the server that "distributes the ratings" (metaserver). They have your rating from the update (UTC midnight) and the games you played today, so they can calculate your current rating.
Now, if a server get's switched, the new one still gets your rating from the update from the database, but they don't get told the games you played today before that time. They are still saved, but the "shortcut" to send them to the metaserver doesn't work anymore, becase they got sent to the "old" metaserver that is now offline.
That means to the new metaserver it looked like you didn't play any games today, which is exactly what you saw.
That bug will need to be fixed, of course. But it seems to explain what happened.