Mortified by son's inappropriate behaviour at school!

My son is 4 and goes to a special school. He has high-functioning autism and sometimes his behaviour can be unusual. His teacher told us he had to be taken out of the soft play at school because he was going round lying on top of all his classmates and moving in a rhythmic fashion! She said he was very focused on his movement and had tantrums when pulled off the children. One tiny girl got quite upset and I don't blame her! My son has never behaved this way at home and he is with me constantly. He has never seen anything sexual nor has he shown any sexual interest or behaviours. Which leads me to think that although his behaviour in the soft play may have looked sexual to an adult, I think he was in fact pretending to be a caterpillar or a whale as he has a thing for both of these creatures. In particular he loves the Snail and the Whale cartoon where the snail rides on the whale's tail. I have told his teacher that I thought he was being a whale, but I still can't help worrying that someone is going to get the wrong idea about his behaviour. I don't know if I'm worrying too much, but that kind of inappropriate behaviour could potentially result in a visit from social services. 

We have stopped allowing our son to lie on top of people to play or for a cuddle and we will make sure he is always supervised around other children. There is a team of teaching assistants in my son's class and I see them every day. I'm so embarrassed about my son's behaviour that it's now hard for me to face these people and I can't help worrying what they might think. I also suffer from an anxiety disorder which doesn't help! Do you think I am worrying too much? Should I have another chat with my son's teacher to make sure she doesn't get the wrong idea about his behaviour?

Any feedback will be much appreciated!