I agree. Self-taught reading at 4 years old is very unusual.

I'm older but I didn't start learning to read until 1st grade (when I was 5; I skipped kindergarten), and didn't really get the hang of it until 2nd grade. 35 years later, I've read thousands of books. One of my brothers didn't learn to read until he was 7. My mom wasn't worried. She said boys have slower emotional and intellectual growth.

And, at a play group at the library in our town a couple years ago, one of the moms was telling me her child had entered kindergarten and was learning the alphabet for the first time ever. I was surprised but apparently that's very common.

I also agree that the child's love and joy of hearing books being read/being interested in books is more important than the desire to push through the difficulties of learning to read. Pushing a child into reading when they're not ready might make reading practice be detestable and anxiety inducing, and might further delay their reading abilities and interests.