Agree to agree

Working for a General Contractor who signs my Agreements, which are short but to the point. When his customer wants a change I assess the request Design and make a drawing to scale, price the change properly. Submit breakdowns in the price and show how it amends the original agreement and Draw schedule. Most of the time I e-mail him the whole ball of wax. He will call me and try and negotiate the price. I'm use to that stuff but once he sells the change to the customer he never returns a signed copy of our change document. If we don't have this change order signed and in my possession it makes it difficult to schedule and proceed. If I pick up and move that always cost me money. Lately I email him after phone negotiations, ask him if he sold the change yet and is he clear on all aspects of it. His last e-mail said no reason to go over this any more we both know what's in it. You can do it you don't need anything from me.
Now I look at that e-mail as agreeing with my change agreement, and if he doesn't give me the signed copy back I still have a binding deal. I know I wish I had more but if that's what makes him happy and I have a binding agreement with that e-mail he sent I'm just find with that.
Anyone have anything else to add to this. Or experiences like this.
Mike