Is this very early testing picking up a pool of kiddos that are precocious learners, or, more likely, due to demographics (dual income families), have had multiple years of academic daycare or preschool? Can you call a program that identifies this way a "gifted" program?
Consider the possibility that your school just has more gifted students than would be explained by a completely random distribution. There could be many possible reasons for this - high SES area, nearby universities that have a significant number of faculty living in your town, other high-tech industries that attract intelligent, educated people. What fraction of the town is college graduates, and how does that compare to the average nationwide?
Or it could be that they are picking up on academic daycare/preschool experience. I'd probably bet on the former, though.
