this is a common thing.
as stated above, most likely a plan missed the curfew and the plane was just returning to base.
other possibilities is that the runway was slick with something (water or ice) and was deemed unfit for the plane to land on it at the time. In this case, it would also be a return to base.
last possibility, it was a plane landing for an emergency, or something like that. Again, just an RTB flight.
I'm the guy... Porter Guy