Originally Posted by Jeff767

The flight in question went out full. The dispatcher probably identified it as a flight that might be load restricted. Delta is being very proactive with that to insure no delays. As the flight got closer to pushback the restriction was not needed and all seats were used. People always have priority over cargo unless it's for a medical emergency or aircraft parts needed to prevent a downline cancellation.
The flight time was longer then usual for this time of year. In addition as mentioned there are many maintenance issues that can increase fuel burn. A simple example is a generator inop. You can go but must run the APU and use its generator for the entire flight. The APU itself has a significant fuel burn and the APU inlet door creates additional drag when open.