Whoa!

Ok... it was Sunday, I wandered downstairs bleery eyed and got myself organized slowly I admit that... Later when I was more awake, and I knew that I had to get ready for my Tai Chi class, I walked over the the stairs and got ready to put my foot on the first step when I saw IT!

Directly at the level of my face was a dead mouse lying on my stairs! I let out a scream that made everyone come running. Except my beloved pets of course, they care nothing for my panic.

Now here are my questions in no particular order:

Why did my mouse friend decide to perish on the stairs?
Did I step over this thing on my way downstairs?
Did either of my pets participate in the demise of the vermin? (unlikely, I know)
Did my little friend die of naturally causes?

and lastly,

How long until I stop freaking everytime I see something on the floor in the dark?