First sign?

I've been trying to use sign language with N. I'm not all that consistent with it, but I'm trying. I think he used his first sign on Saturday... we were in the car, and I was sitting in the back seat with him. He's gotten into the habit of wanting to nurse while we're driving (started that bad habit when we were driving the 4 hours to visit his Babka), and I'm quite sure he made the sign for 'milk'! Usually, his sign for milk is to grab at my shirt and try to pull it off.