"there is now a Preview site in addition to the Public site."
No, the Preview accounts are a whole different animal. Are you sure you're looking at your original 365 account and not a Preview account? The Preview accounts are separate accounts according to MSFT and will get deleted when they roll out the new version. which their latest info says will be "sometime in 2013". There's a lot of confusion about the upgrade which is a 2 step process - there's a preparatory upgrade (SU4) which is happening now, but that isn't the same as the account conversion to 2013. It's possible the SU4 upgrade broke your dns records - try going to admin>>domains and resetting the site address to your domain.