Yet another rodent story

I was changing my bed, flipping the mattress when I discovered a little mouse poop on the base, right belowy where I lay my head. I think this explains the mysterious breathing that freaked me out in the middle of the night about a week ago. It was pitch dark, after what felt like hours of mysterious thumping, tapping and assorted unwelcome night noises. And then suddenly I heard this quiet breathing, and it wasn't mine. I thought maybe it was something biggish (possum) in my room or something really big (cow) outside my window but it went away before I worked up the courage/motivation to check. A little mouse visiting my pillow makes much more sense though, perhaps the one found dead in the trap the very next morning.