Actually, it is slightly over: ....
I have also found GCM mileage can vary in the order of 150 miles away from the "official" mileage when determined via the AA RTW desk. When booking a mileage dependent routing (eg DCIRC29SA) that is near the 29k miles, I have alternate cities already worked out so they can be easily substituted into the itinerary - makes for a happy AAgent at the RTW desk - "glad you did the homework before calling".