If he's not worried, I wouldn't be. I know that it's a pain, but if you worry him about it, he'll worry. Can you ask the class teacher if he has any friends in the classroom?

DS has very few friends, but it worries him so I'm now involving his teacher. We have playdates and he's great one on one, but not at school with the unstructured play.
Thanks for your reply. How old is your DS? Good luck.

It's good that my DS isn't worried now, but part of me thinks that perhaps it's a good idea to try to sort it out now before he starts to possibly worry about it down the track?

I plan on speaking to the teacher, but to be honest I think she has her hands full with a child with special needs in the class, so I worry if she has the time and energy to observe the social interaction of my quiet and well behaved boy.

I'll stop being worried if there is research to say that kids that don't have friends at his age go on to be confident adults!