When they don't hit a milestone

This week we found ourselves at the DMV to get a state ID for my son. It hadn't occurred to me that he needed one, but not being in a public school , he doesn't have a school ID, and he has had a few things come up recently where he needed an ID.
I filled out the paperwork and watched as he signed his name is LARGE caps on the line , and needed to be reminded how to spell his last name. I watched as he stood for his photo just like the other 17 year olds getting their drivers license. The ID looks just like a driver's license , but it's not one. I pretend that I'm not bothered that he isn't getting his license, that he will likely never get it. It's another milestone that we are not doing.
The truth is, I'm not upset for me, but I am worried for him.
We all worry as parents, right? But not like this.