I guess what I mean by hypersensitive is the bizarre obsessions our son would have as opposed to those people who are just "too sensitive" as others say. And we found the same thing to be true as you did; he'd hear of something happening somewhere and take off with it. Or, one bad experience with flouride meant, to him, that all future visits would be horrible. To this day, he has a lot of trepidation of throwing up and reacts extremely when someone around him is sick or has been.