I wish I could tell you one is it. But I've had this problem and there was more then one. Babies came along as well. And I'm afraid of mice. I remember this one time, I was watching tv alone in the living room, and I saw this mouse come out of the kitchen. The next day, I saw it walking right in front of my feet. I yelled! We took care of them of course. There's no room in my house for me and mice. I know they are smaller then me, but I still feel awful when I see one around.

Hopefully, you won't see another one.