There were still downtown rooms available at 1:01pm. They may not have matched the dates or number or guests but there were still rooms. I had two friends get downtown rooms between 1:01 and 1:30. There are Sunday night only rooms available right now downtown on the portal.
That said I do agree rooms seemed to go faster this year than last. However since Gen Con won't tell us how many rooms there were. How long people were given between getting assigned in the queue and a number of other things, it is just idle speculation as to why it went quicker.