Interesting things happen when the last flight of a trip is delayed beyond midnight (at least I think that is the trigger):

1) The trip disappears from my profile on the web and on the iPad app;

2) On the iPhone app the trip info is still there, but... the upgrade list info shown appears to be for a different flight. My guess is this is upgrade info for the next flight with the same number. Thankfully the gate screen still shows the correct one. ;-)