Mike, if you look at rules 4 and 7, they address a safety line that no flying may be behind, but do not specify where that line must be (ie, on the runway edge, 25 feet out, etc). The rules also specify that a pilot may not fly within 25 feet of others (excluding takeoff and landing) with the exception of himself and helper(s). Looking at these two rules, it looks like walking onto the runway and hovering in your face is permitted, but flying behind the flightline and touching the model is not. Obviously I don't think it's a good idea to be walking out on the runway unless you are flying by yourself and no one else is getting ready to fly.