::Well, you could try to get it out, but it probably likes it there. What you need to do, is go to a local pet store, buy a mouse(preferebly frozen, then thawed)and set it near the entrance. Although, thats not very wise. Other animals may be attracted to that. But if it isnt doing any harm, than you should leave it alone.
I will try the mouse as you said. Like I said I'm not really worried about him myself buy my daugther seen it go into the frame of the house.. My wife will never find out that it in the frame of the house...I hope.