My son has repeated himself in periods, always connected with anxiety.
The first was when he was 2 years old and started in nursery school. He repeated "it's naughty to fight".
The second when he was 3 years old and becoming aware of traffic. He repeated "it's dangerous on the road."
The third was when he was 6 years old and become aware of death/physical vulnerability. He repeated "No owie on me."
In the store, your son might have felt everything was unpredictable and out of his control, so the repetitiveness and the control he feels over his own speech could be comforting.
You might want to look at this article about stims and their sensory nature:
http://www.tsbvi.edu/Outreach/seehear/archive/mannerism.html #Chart
Good luck with everything.
That's very typical for an autistic child. I'm assuming it's either echolalia or just a verbal stim. Does he echo things he hears others say, or that he hears on TV as well? You can either choose to ignore it, or give him a prompt of "One time" when he begins to repeat, or try to steer the conversation into something more productive. My husband and I took our Tyler to a store today called gamestop where you get 100 million games for your xbox or playstation . Well we got there and Tyler went crazy of course he kept saying things then whispering what he just said he does this all the time is this normal behavior. Then he acted up kept pulling all the games down had them all in one great big pile all over the store what a mess.Just wanted to add our dd does this too. She has several 'catch phrases' that