The only time I've worried was when he was younger and would freak out in crowds --- for example on trips he would be fine camping, he'd be fine at the zoo or an amusement part but a crowded tourist place would cause him to behave very strangely --- almost like a wild animal --- and he would be almost incoherent when asked why he was acting the way he was. He'd say he didn't know --- but his behavior was definitely weird --- running off, hiding, purposely getting lost, darting around and having outbursts --- not shyness but something else. But since that was at ages below 10, I didn't pay much attention and just kept him out of those situations, in school he had no such problem and it seems to be something he's outgrown but I doubt he'd ever do well living in the city or be happy being in crowds of people. It was at those few times though he would actually act autistic but to me if it's that rarely then it's still within normal and he wouldn't need any kind of label.
Similar to my feelings on ADHD --- a real disorder or chemical imbalance does exist but the labels and the drugs that go with the label are given out too commonly. If you have a child that doesn't like to sit still for 6 hours straight they can get that label ---- but they might be quite normal. I think sometimes the problem is really trying to put normal square pegs into the wrong holes, they are normal but the situation they may be in is what doesn't fit.
There is no good treatment anyway. I am glad my son was diagnosed because it finally meant that it "wasn't anything I did wrong." However, there are no drugs to fix it (and I am glad), and "social skills classes" are of no use as I have found. Unless possibly your child happened to find a like-minded soul for a buddy in one of these classes. Mine was always the most highly-functioning. But figuring out the right behaviors to use in the lab with other auties si very different anyway from navigating the real world with the rest of the human population!
So keep doing what you are doing and make his childhood happy. Hearing on this thread how many people had miserable childhoods reminds me why I decided to homeschool my son.
I don't like to think of him as a diagnosis. He is my son. He is just fine the way he is.