Hi 7thgentxn,
It's great you are lifting together. Don't worry about it - I see perfect linear progress and you just started. Keep at it for a few month like that and he'll already be quite strong. Eventually, when these curves flatten out we'll see if anything is unusual (unlikely).
Make sure to feed him well. What I would worry about is form - make sure he learns the lifts properly. There are some pretty decent SS coaches in Texas!