I have a different version of this same question - my DS 5 is huge leaps ahead in reading and understanding concepts - particularly science - it is astounding to me sometimes the connections he makes. But I would not describe him as "mathy" and its unclear to me (maybe I should ask the gurus) what part of the testing shows innate math skills. But what I have noticed is that he learns math best by reading about it. Despite having a phenomenal memory he is not consistently right when doing simple adding and subtraction - and far too frequently says 5-1=5, although will count it off correctly. Yet he knows and understands from the sir cumference books and cyberchase and other places things like area, diameter and circumference. He just read a fabulous book, the cat in numberland, and is now getting placeholding and concepts like infinity.
Have you read Developing Math Talent? They say it's extremely common for really mathy kids to lag in computation compared to their grasp of the concepts. My DD is learning to add fractions at the same time as she memorises her addition facts to ten and her times tables.
