Its freeway/highway driving. I'd imagine I do more of that than most so I wouldn't expect my mileage to diminish when I'd be willing to bet most people here have short commutes or do more city driving than highway driving, particularly when looking at the miles driven threads and knowing how few people have even gone over 5k on their trucks.
Of course laying into the throttle will guzzle the gas.. but all things being equal if I can keep my RPMs below 1.8 I feel like for this truck I should be seeing better fuel economy similar to others here, especially since elevation and (to date) climate does not play a role in my mileage.