ME TOO!!!!
But I have to wonder - did the President stop in his tracks because he discovered that his usual detail wasn't around him and look to see where they were?
That tells me that the SS has done their job - getting the President so used to having his SS detail around him, that he stops when they aren't. Good move.
Freeing his lead agent from the Chilean "scrum", even better move!!
If you watch the video .. you can see that there was quite a clammer of yelling and activity. The noise and probably peripheral vision of a lot of activity right outside the door caught his attention, and he reacted instantly. The confrontation was not that far away from him.