My teenage aspie son has always done that. He also, when he was younger, did the traditional echolalia where he always kept repeating back whatever was said to him. I did that to a lesser extent when I was younger (and drove everyone nuts doing it, lol; it was long before I was diagnosed with NVLD with overlapping A tendencies). I still find myself repeating words inwardly a lot of the time, and my son tells me that he does that as well; sometimes he does it verbally but mostly by now is able to keep it quiet.
But I don't think what you're describing is all that unusual with aspies, my son is like that and other aspies I've known are, too.
_________________
Queen of the anti-FAAAS. FAAAS does NOT speak for me and many other families!!
Life is not about waiting out storms, but learning to dance in the rain-Anonymous