Wow... totally same thing here!! DD will be 9 in three weeks. She is also going to Science camp this week and I, too, put her in a group with older kids (9-12). Yesterday, when she came home, she mentioned that she felt very young and a little uncomfortable when it came to socializing with the other kids. She is an extreme extrovert who has many friends and loves to meet new people. I am chalking this up to first-day 'ickies'... a term she coined for that yucky nervous feeling you get in your stomach when somthing makes you uncomfortable, rather than that she does not fit in with the older kids. Maybe this is the case with your DS, too.
If you figure out the right answers to anything related to parenting a giftie, you are one lucky person! If my mother's day present was relative to the amount of time I spend worrying about DD, I am due a trip to Hawaii and a Lexus SUV for this year alone, LOL.
PS - did he like science camp? DD is having a blast. They made polymers into rubber balls, learned how to develop a video game and how to dust for finger prints.