Yes, males can breed at the size of snake you've described, and yes, they do often go off their feed when looking for a mate. It is a bit late in the year for this to be happening right now, but do you have a female that is caged near enough to this male that he can smell her pheremones (sp?)? If so, you might want to separate them even further and give him a week or two to come out of that breeding mode.
Right now I wouldn't worry too much about it so long as he is still in good flesh. However, if he goes another couple of weeks with no food, you might try to brain the mouse you offer him. Sorry to be gross here, but sometimes my adult females will be less than enthusiastic to eat as they are filling up with eggs, but I want them to eat as much as they can for as long as they can. To entice them, I will sometimes squeeze the mouse's head until some blood/brains/fluid come out of the nose and/or mouth (the mice are obviously f/t) and then offer it tot he snake. This ALMOST ALWAYS works!
Let us know what happens with your snake -- Darin