Urgh I know how you fell. I was sitting on my floor a few weeks ago, and then a mouse ran past my fast, a LIVE one! I don't know which of my kitties did it, but eeew it was nasty. I don't mind mice, I just mind them in my bedroom going about their business!
You could try putting an extra bell or two on his collar. Thats the only thing I can think of though.
