Yes, I think Churchill got all his bargaining power allowed. To his credit, however, Stalin is abiding by the deal.
Stalin has bigger fish to fry than Greece. He was a very patient man, looking at the bigger picture and long term. The main objective for him was Central Europe, particularly Poland, Hungary and Romania. He was also backing Tito in Yugoslavia. Stalin got the far better of that deal, and was looking to keep the Lend-Lease rolling, and to get what he could out of Japan when the time came.
Why risk screwing up all of that over Greece?