I have noticed something similar with my fourth grader. His type written work is more well thought out. I think it is just that he has to slow his mind down to type while he can let it race when he is using hand writing.
I just had a weird experience with him though where he had read a poem and was way off the mark when I asked him a question about the poem. I thought there was no way he didn't get what the writer was saying. Then he handed me what he had typed and he had it right. So, I think it is the same thing where his thoughts are going a mile a minute when he is speaking or writing, but he can't type fast yet, so he is forced to slow down.
