Yea, there could have been a reason that 1 seat had to go out empty. The fact that the GIDS showed 0/0 leads to that probably being the case.

It is also possible that a pax was "boarded" but not physically onboard, and they caught the error just at dept time and corrected the manifest. In that case, they should have grabbed the 1st nonrev on the list. How long did you stick around?

I don't believe the list is automatically rolled over. I think the gate agent has to do that, but they would usually just do it w/o being asked.

Did the 2nd flight go out full?