My nearly 7 year old is a pretty fluent reader as well. But don't stress.. I have a friend who's son is going in to grade 1 this year at an independent school, and they don't even start teaching reading until they are 7, so he is still doing abc's. They are at such a ripe age for grasping it, I'm sure it won't take him long to take off. They do rely a lot on reading with their work in general I've found. But there is reading recovery for those that need to catch up, and you can probably volunteer to help with that to learn how to get him reading.