My parents had 2 mice over like 15 years. As long as you don't hear them in the walls after you catch this one, you should be ok. Sometimes they enter in attics of basements. We knew we had one because there was a bag of soft tortillas that was crewed open with crumbs by it. We used a 'humane' trap, and let him out in farmland...
Then there was the time that I came home and saw a bird fly through the kitchen from the front door. When I got into the kitchen and it flew by my head I said "HOLY SHIT IT IS A BAT!!" He was a little more difficult to get out, plus animal control wouldn't come out for a bat. I (lightly) swatted him out of the air with a spatula and he landed on my foot. As he went to fly again, I was able to catch him in a bath towel and fling him out the front door. Of course 6 months later they issued a warning to call animal control because bats were found in the area with rabies. I guess it is a good thing I didn't get bit.
Hmm...if I only have 2 mice over 15 years I'll be very happy. We just had an early cold spell here which probably made him come in. I've lived here just over a year, and never had any mouse issues before now (no piles of feces, no boxes or bags of food eaten through). I'd prefer never to have any more issues in the future either, I find them rather gross.
I've also heard horror stories about hantavirus and the such, but apparently only about 30 people per year in the US actually contract that. Probably not something to worry too much about. Obviously I'll be careful if I run into any mess piles, but I was surprised to see how rare that virus is considering how much I've actually heard about it. (I have a little bit of anxiety at times, so rationalizing things like that using statistics helps me out haha)
I don't know what the hell I'd do if I had a bird or bat in my house. OMG I don't even want to think about it. Chasing a snake out of my garage, getting a duck out of my window well, and now this mouse are about as much as I can handle.