What does interacting with peers look like at 2 1/2 (ASD)?

Hello,

My 2 1/2 son has "mild" autism. Today, when I dropped him off at MDO, he went straight for the dress up clothes, hats, etc. and started putting a hat on himself and then put one on a little boy in the classroom and was just so tickled that the other kid was wearing a fireman's hat. He was looking right at him and laughing.

Then, at pick-up time, he was playing "with" other kids with megablocks. I guess it was more parallel play of course but I was happy to see him with other kids and not by himself.

The teacher also said that during the day he sat down by three little boys who were playing with cars on a rug with tracks, etc. and started to play right along with them and was pushing cars (and not just looking at the wheels). The teacher was so excited to see that, that she wanted to take a picture with her phone but her phone was dead.

Should I feel encouraged? Sometimes, I feel like my expectations for my DS are higher than they would be if he was typical. What does peer interaction look like at 2 1/2? Do they still mostly play side by side? I rarely see even the typical kids in there having "conversations" or really playing with each other but rather playing side by side but maybe I'm not seeing it all.

The teacher says she is seeing him change since he started in that class just 7 weeks ago. I guess my husband and I are very cautious and don't want to get too excited. What do you think? Thanks!