Get over your denial:), I am slowly getting over mine too. DS4 started reading at the same age yours and now reading at second\third grade level. I volunteered a few times at his school last year before the summer started(class of 3-6 years old) and believe me he was at par with 6 years old. Now this year we keep wondering what to do with him as even a grade-skip won't help, not that we are thinking about it as he already has a summer birthday and we do not want him to be bullied by older kids or be exposed to the information which is not age-appropriate.
So.. the earlier you get over your denial, the earlier you can start worrying;)