I think the fact that all the notifications came through means that the settings weren't incorrect, and DND would only prevent them from lighting up the phone screen (they'd still appear if you hit the home button to light the screen up).

Although it could have been a temporary glitch with either UA's systems or the APN (Apple Push Notification) servers, IME, issues with notifications can also happen if your phone has tried to latch onto a wifi network that is protected by a paywall or other login screen (i.e. Boingo, etc.) that hasn't been passed/agreed to/etc. The phone can sometimes remain in a limbo state where it thinks it's connected to the Internet via wifi so it doesn't use cellular data but data actually isn't coming in through the wifi connection. Once you either manually disconnect from the network, turn wifi off, or move out of range of the access point, the phone reconnects to the Internet via mobile data and all the notifications will then stream in.