In before the lock.

I don't like it when people that I don't know grab my wheel, unless I am participating in a group ride or a race. I ride with people that I know and trust. Having someone that I don't know just come up and grab my wheel makes me very nervous, especially if it is unannounced. I have no idea what a strangers experience level is like and if he crashes me I am going to be very upset about it. Now if he announces himself then who knows, might end up in an impromptu group ride.

Also, if the guy let you know that he didn't appreciate it then you definitely should have just dropped back and let it go. There is no reason arguing with another rider that doesn't want you on his wheel.