This was a concern for me with one of my girls. I use a heat lamp to warm up the head any body a bit before I offer the f/t mouse/rat. Make sure you're feeding at night too at least around 8pm. With trouble feeders its good to make sure the room is nice and dark. It makes them feel much more confident. You can a table lamp or something fairly close so you can see though. Don't stand around gawking at the little guy either. If you want to monitor to see how its going try not to make too many sudden movements, and try to stay about five feet away.
To answer your original question, Don't worry about the last time he was fed. Try and wait a week to leave him be. Waiting will only make his feeding response stronger(from being hungry). While you wait keep an eye on his behavior. An active ball is a hungry ball. If he strikes make sure to tug on the tail of the f/t feeder, or any body part, without touching the snake. It'll help stimulate the feeding response too. Finally, don't get too worried!