three year old rocking back and forth?

[VioLetsMum1]

DD was shattered after the morning out. Got back home and she went for a nap. Bout half hour went by and could hear her babbling to herself. Had a peek in and she was knelt on the floor, a book at her knees and she was rocking back and forth muttering to herself. She didn't seem to be concentrating on the book though. I accidently made a noise with my foot and it was like she snapped out of a trance. Went on for a few mins. Is this normal behavior? I've never seen her do it before. Googled it and loads of pages about autism came up but as far as I know she has normal development and infact above average in speech etc. It just perturbed me a bit I guess.

I rock when going to sleep, It's a comfort thing i think.

I find it comforting to rock. I think it is a sensory thing rather than a symptom of autism( people who have autism can have sensory issues). So when I rock and am seeking some sensory input to calm myself. I am not very knowledgeable about all the sensory stuff but I know my ds does a lot of things for sensory input and also the reverse, he can be overly sensitive to things like noise so has to wear ear defenders.

If it keeps happening it may be useful to keep a diary of when it happens and video it if you can. It can help build up a picture of what is triggering it. I rock when I am forced to sit still or stand still for too long. Ds spins when he is in a busy place to block out all the noise and people.