I said this to a coach once and he came back a little bit later and said "You agreed with me, why haven't you been calling those fouls I pointed out??" I had to explain that acknowledgement of his comment is not the same as agreeing with him.

Now I say "I am watching everything coach." This reminds the coach that I have to watch more things than just the particular call he is looking for, and reminds him that I am on top of it.