well even if its downloaded when you go to system update it will still need to go online to check the one you have is the most recent.....but idk, maybe you did catch it in time......on a final note im pretty sure to update you need to press A (or confirm on the touch screen).....but then it will ask you to agree to the T&C's which can only be accepted on the touch screen iircHmmm I don't think it will pop again but even so I don't think that the update will automatically engage if you press A. I believe it will need some more confirmation actions.
Also I went in my settings menu and to the update system button and it still asks to connect to internet to download the update. This reinforces my thoughts that it is not downloaded but just spotpass notification
Ninja'd