Quoting March 2013:" I don't know. I could just see her form. Just as I was waking up she turned around and went back to ... [snip!] ... mind and didn't need us. She has talked like ones or twice in her sleep but thats it. Normally she sleeps pretty hard. "
I know that right when DD turned 3, she started sleepwalking. She would come out into the living room and just look at use then go back to bed. She's no autistic but what you are describing sounds similar. DD only did it for about a week or two.