I really believe science is FOS when they say animals can't reason. I have seen too many of them use their reasoning ability, this goes for domestic as well as wild animals.
I have no doubt that the Mama BF knew I was there, I'm about 100 % certain that she knew I was in the deer stand. They don't miss much in their environment. I may be way off base here but my theory is, it wasn't a test, but a show of a level of acceptance to my presence. When she stood up I was between her and her youngun. Now had that been any other large predator, bear, big cat, etc., it would have attacked. I wouldn't have been given a warning. Under those circumstances she should have and didn't.
I don't know, I can merely speculate, but since then I let them choose how close they want to get.