Your question was: Standing behind me.
Did you accept his offer for a drink? I'm not sure why you're trying to read body language, when he went ahead and asked you out!..
Yes I did accept the offer after the first time. I don't know why I'm bothered by his body language either but you know sometimes something just feels off or different? Well I never had a guy this kind of behavior. I was just curious. Is it shyness?, possessive?, Just strange.
You may have to ask him some questions to uncover your answers. You can simply ask him why he stands behind you the way he does. Some men do the "body guard" thing...but who knows about this particular guy. Also you may want to ask him if there is anything about you that he is curious about. Some guys are shy to ask questions, some guys are used to women doing a lot of talking, and some guys are just not interested and that is why they dont ask questions. Once he sees that you want him to ask questions, it may just fall into place. Good luck!..
I'm just going to play it out and it will become clear...