It was an emergency maintenance "to apply a hotfix." There are pre-scheduled, weekly maintenances that do what you describe. If an emergency maintenance is to address server stability, it is mentioned in the notes. This happened repeatedly at launch.
If the FFXIV servers need multiple "emergency maintenances" a month on top of their scheduled weekly ones to be stable, across two completely different server host sites (one in JP, one in NA), whoever is managing their server architecture needs to be fired.
