Did you tell him "you need to do nothing more!"I remember a relatively new instructor who happened to be the DM for one of my dives. It was just the two of us plus a DMT. After 69 minutes, the instructor had to call the dive because he was low on air. I surfaced with 1200 and he was at 400. The DMT was lower.
I was very flattered when he asked me how I did that.