Was the club opened longer than usual?
Legally, I know that DC has a decent closing time unlike Maryland and many other locales. Although in Maryland, usually on NYE, instead of forcing the bars and clubs to close at 1:00 or 2:00AM, they allow them to stay open until 6:00AM. That's going to cost the establishment some extra money for staff, utilities, supplies, etc.. Don't know if this may have come into play for the 9:30 that night.