Welcome to this bewildering world!
My first response is, if he's thriving, enjoy it and don't mess with with it. A happy kid is what we're all looking for.
Some kids do great in public school, others struggle to fit in, academically, socially, or both. Most, I suspect, have different needs at different times. Now, when everything is going well, is a good time for you to do your research on what kinds of schooling options you may have, when, and what would be required to access them. At the same time, forums and sites like Hoagies can help you see what kinds of issues may - or may not! - arise with your son over time. You have the freedom of some time to think about what benefits - or problems - could make you want to change schools. It really comes down to finding the right fit with your kid, rather than the schools themselves.
My impression is that it's not uncommon for the need for different kinds of schooling to grow as the kids do. Grade 1 math may be boring, but school can still have some novelty and fun social interaction. But when they're still doing the same math in grade 4, and their peers are really starting to take notice of how different they are - well, then you might need a different kind of environment.
With a happy kid, and teachers who care enough to identify and support, it sounds like you are off to a great start! Good luck.
