Wow, that is not an excuse to kill it. Live and let live, this is a living creature, it won't do anything to you unless you shove your finger in its face like badeaguard did. You're a giant to the mouse, it will run away, not fight you.
Jesus, how many animals do you kill just because it's better to be safe than sorry? You kill hobos too?
And yes, I've seen inglorious bastards.