My son was like that. He read for me when he was 2 1/2 but wouldn't do it in front of his dad. When he was about 3 1/2, his dad caught him one day reading over my shoulder something on the computer screen. I asked my son how he knew what I had just read silently and my husband said he saw him read it. His older son had also taught himself to read.
At 4, in his musical theater class, he was silently reading the script for "Babes in Arms" and the boy who was reading lines next to him lost his place so my son told him the next couple of words. The boy later asked him where he went to school and what grade he was in. My son had never even been to preschool and didn't know what to say. When he was asked this question by someone else at a grocery store after they saw him reading out loud, he told them he went to funschool.com but he still didn't know what to tell people when they asked what grade he was in. This has always been a problem. He finally started telling people if he were in public school he would be in __th grade (whatever grade his age mates were in).
I guess he got tired of me asking him to read in front of adult relatives and once when I asked him to read a sign out loud for his grandparents he loudly said, "Read? I'm too young to read!" and went back to what he was doing so I quit asking him. He didn't seem to mind reading for other kids for some reason and he enjoyed letting them spell out words for him because he could usually identify the words, especially science related words because his favorite book at the time was a children's science encyclopedia. He did enjoy the attention he got from other kids for this. Those years before he was old enough to start school, before we knew the advanced reading would be seen as a problem by our public school teachers, were really fun.
