The guy I need to speak with is a supervisor. He's one of those touchy-feely kind of guys, and I trust him. He's one of two guys I know who I let touch me in any way besides the customary cordial handshake (the other is my dad). However, he knows nothing of my abuse. I need to let him know somehow that it's not okay to startle me.
I'd say that if you feel as comfortable with this supervisor as your post indicates, he would certainly understand if you told him first of all how much you appreciate his demeanor with you, and secondly that you have a request about being startled, that you really need him to always approach you from the front and never try to startle you. I suspect that will be enough for him, but if not you may want to have a backup plan in concert with your therapist before entering the discussion in the first place.
Lots of love,