yeah its been used for a long time.
cool though that you figured out that when you look someone in the eyes they almost always take their eyes off of what you are doing and look right back at you. Even if they are starring at your cards or whatever at the beginning they will most likely sense you looking straight at them and will look you right in the eyes. It works best if you ask a question at the same time because then they see you looking at them for an answer. Something like "what's your name?", "how old are you?", "are you right handed or left?", etc.
It's funny tha you mention that because now that I think of it I always do ask questions, usually subtly related to the trick:
"this is a black seven , correct?" [ before color change effect]
"have you seen this trick before?" [tricks with twist endings]