Wow Debbie!
I'm so pleased to be hearing that he is being tested is so much depth! This way you can be confident that if they end up sending him to 4th grade, or offering "Art of Problem Solving" independent study during math for the first few months, that he won't be developing bad "Gaps."
((roll clip from Wizard of Oz:
Munchkin to Dorthy: "Are you a good Gap or a Bad Gap?"
"But Sir, I'm not a Gap at all!"
end clip))
What curriculum were you using at home? How far did you get with it? What about that famous "skill" stumbling block - the times tables? How old is your DS now?
BTW - I wouldn't actual worry about perfectionism yet. Perhaps he's just good at remembering what he's learned and what he hasn't and is trying to do his best. It will be key for him to get a brief "tutoring session" on the stuff he doesn't know to "see how fast he learns" and for the distinction to be made clearly and verbally and check to be sure he understands the difference. I think you would have gotten some hints if he was having issues with perfectionism. Do you see this at home? And of course, the hints of perfectionism, or it's full blown version is one of the key reasons for grade or subject acceleration. ((shrug)) It's the Nitrogen buildup thing.
Yippee!
Trin