A mouse in the house

Imagine my surprise when I went into the first floor bathroom this morning to find a mouse in the toilet - and unbelieveably enough it was still alive! Where did it come from? I don't know, but I suspect that it snuck in the front screen door sometime last evening - maybe through a small opening in the bottom of the door, but maybe not. Crazy person that I am, I went into the kitchen and got myself two plastic containers to use as a mouse house. We (the mouse & I) had a bit of a scramble - still in the toilet - until I captured it and marched outside to let it loose. I trust & I hope that this mouse doesn't managed to find its way inside again!