Since there isn't a higher score, and there seems to be a process to move on to the next round for GT services, I wouldn't worry too much. But the school should be able to answer your questions. Usually, when the CogAT is given, the results are also given with some sort of profile (a number and a letter, if I remember). If I were you, I would ask the school if they can give you more specifics about what your kid's score means (do they have any other data to share, like profile numbers?), and also what happens next in the GT process.
