It sounds like you've gotten a lot of support here already for trusting your instincts. As much as I am put out by GT programming in many of my local schools lumping a lot of above avg achievers in with truly gifted kids (calling kids with IQs of 135 and 105 all the same thing if the 105 kid is a higher than avg achiever), I've become less & less certain how much we can rely on IQ tests to be totally accurate.
One of my dd has wild swings in IQ scores. In her instance, I'm not so certain in my mind where she falls, so I don't have as many instincts to trust in regard to her. Your son clearly presents differently than this one set of IQ scores shows and you have enough experience with truly gifted kids that I wouldn't worry that you are misinterpretting what you are seeing in his achievement.
