I think that you do a great job with your kids...and you always seem to be done with their classes and moving on to the next level of that subject or another subject...maybe it was just easy for him and he was too advanced for the test

You can't worry about it now, he's done...and he probable did just fine
I have finished exams that with hours to spare...double checked my work to eat up more time and then finally left...when others didn't finish all the questions with the allotted time...and I did alright on the tests...so don't worry, it happens