DS 6yrs is being assessed for AS.
I have noticed for the last couple weeks he has been waving at no one
As we got out of the car and walked to front door he turned and waved down the road. When I asked who he was waving at he said his friend. I said I cant see anyone and he said he has got a green T shirt on and just walked in the house. I have also seen him do this from his bedroom window.
Two days ago we had gone for our usual evening walkabout (its mad holiday time where I live so we tend to go out 8pm ish when its quiet) We walked down the hill and he looked accross at a culdesac and said Nanny and Grandad are over there look. Well I looked and there was no one about. So I told him there is no one there. He just said oh well I thought it was them as they had hair like Nanny and Grandad and just carried on skipping.
Tonite on the way home from walking dog we were walking through town and DS was waving again. I asked who he was waving at and he said "oh one of my friends they are always walking about" then he was quiet (well touching windows as we walked) and he said "maybe you will meet my friends one day"
Now I know he has a vivid imagination and plays role games by himself in his head. He does say he has pictures in his head and he cant switch them off at school and he has got to play the pictures out? Also things like a fiver, tenner, twenty pound note he says five dollars or ten dollars. Tonite he was inside a phone box while waiting for a taxi (it was quiet inside it and there was a huge que so that was where he chose to wait. He shouts out Mum! I have found 8 scents! 
No matter how many times I tell him our currency he says he likes the sound better?
It is starting to concern me and did give me the creeps as by his face tonite he was really seeing something. Does any other Mums notice this in their children?