Amen to "trust your gut". There have been only a few times when this has happened to me, and I can attest that it never lies!
I think the BG is also running thru his script, and this is somehow broadcast to anyone who has his ears on; especially the intended victim. When you respond by running thru your own script, he senses that just the same. No matter if it's a BG, or dog or zombie. If you are thinking thru how to go about winning, he "feels" that. If you are thinking thoughts of fear and resignation, he feels that too. "Ain't skeered" is the correct answer. He starts to look harder at you to find out why.
Think of those times when you feel that things are amiss, but you are not armed. BLUFF!!!!!!!!!! -But bluff with your gut, and he'll back down.