My son never rolled his hands and IS on the Autism Spectrum. He made eye contact and laughed and his pediatrician said he had no signs of Autism at his 12 month well child visit. He still makes eye contact and laughs A LOT! He is a very happy child who gets speech and other therapies at his pre-school.
I think your doctor concerned you for no reason. In my opinion, all parents, especially of boys, should keep their eyes open for language development starting at 12 month. Make sure your baby points to objects and tries to repeat the sounds you make by 12 months old.
At our 18 month well child visit the pediatrician (a different one) raised some concerns about his language development and that he wasn't interested in drawing with crayons or feeding himself. Since my husband and his brother were late talkers we decided to hold off for another 6 months. At 2 years old there was no significant improvement so we had him evaluated and started Early Intervention, which is when a therapist or therapists come to your home. We saw an improvement right away. If I had to do it over again I would have gotten him evaluated at 18 months and started that much earlier.
The evaluation and therapy was playtime for my son. He loved spending time with his therapists. He's in a special pre school now, but we expect him to be going to a general ed kindergarten in 2 years. We have every expectation that he will be a happy, independent adult. That's what we all want for our kids, right. Every person's path is different whether there are issues or not.
My advice to you is, forget about your worries for now, just keep your eyes open for pointing (9-12 months), speech and any aversion to textures. I've shared my story with you to emphasias that its way too early for you to be worrying about this and that even if there is an issue it can be dealt with and you can still have a great outcome.
If you are still worried about this, call a developmental pediatrician. It may take several months for you to get an appointment, but it will be worth it to settle your concerns.