It sounds to me like he is somewhat timid, and even more quirky that your average grey but I wouldn't say he is a true spook. My first grey was very timid and shy, and acted a lot like Kingsley. She relaxed quite a bit after she got used to me and our home, but that took several months, and she was never comfortable away from home. I would reassure him when he is afraid, continue to build your bond (four months really isn't that long), he will probably always be happier in a familiar environment and just with family, and probably always a little jumpy, but I bet in a year he will be much more relaxed