My guess is that he has worked out the local "Mouse runs"
Weve heard of rat runs - well mice do the same - stick to their regular little route.
All Mr Munchkin needs to do is pop down to the local Mouse Highway and as one runs through ..... its snack time
He is doing the equivalent of popping down to his well stocked corner-shop
Watch him - if you see him sitting quietly in the same spot each day you are onto him .... try sprinkling the area with something like citronella oil -it might put him off and destroy the mouse scent