My son is often like that. Of course, he often doesn't like to answer questions, period. Rather, we tend to find out what he's thinking about or knows in conversations that he initiates or by watching him play. Sometimes we can "sneak" questions in, but most of the time, he will ignore direct questioning (much to our exasperation!).
But, back to your original post, yes - he often retains and pulls disparate pieces of information together, even if he seems to not be paying attention at the time. I think you're right about the "internal computer" needing time to process.
