I am a tester for a major Satellite TV provider and I can assure you that last minute bugs pop up all the time. Products releases and software updates get delayed literally hours before being shipped, pushed or sold. This is all part of the reason that VZW did not set a release date. People like to freak out in a fit of entitlement around here but there are people at VZW much smarter than anyone who posts here.
Yes, last minute bugs pop up. HOWEVER, there is a review for a launch that must be met before you approve the release to the channels. It's reasonable to assume that approval was provided, as phones where shipped. If there was approval, then there was acceptance in it's current state.
Something other than a bug caused this delay.