This is classic gifted behaviour - often gifted children don't want to stand out, because they know they're different. Sometimes school just can't give your child what they need. That's not to say that it's a bad thing just that it's often not sufficient. If they are interested in stuff and actively pursuing interests outside school, then I wouldn't worry - they'll end up teaching themselves better than anyone else can!

All the best

Always Learning
http://www.giftedchildcommunity.com