We have the same thing with our DD4 - she was a sponge before going to preschool, but now is saying things like "I'm not supposed to learn to read until I'm 5" or "but I'm too young to know how to do that Mommy, I have to be older before I can understand that". It is only when we catch her with her guard down that we can see how much she can actually read, or how good she is at math.
DD9 was the exact opposite - she seemed to learn through osmosis when she entered school - if it was being taught somewhere in the building, she learned it somehow and needed more when she got home. It was actually pretty scary and continues to be so to this day!
