Gas mileage on CX-50 hybrid

I've had my CX-50 hybrid for nearly a month and for the most part really enjoy it, but l've been disappointed in the gas mileage so far. My commute to work is 42mi one way and 27mi of that is on highway. I am usually averaging 28mpg, the highest I've gotten is 31mpg. It has gone down to 25mpg before. Considering the car is advertised at 38mpg I'm finding this a bit disappointing. I try to drive pretty conservatively, avoid sharp acceleration and braking, use cruise control to maintain speed, don't go super fast, all the things you're supposed to do.

Does this sound right? Any other tips for how I can improve efficiency?