I hear noises.

This is why I don't house-sit by myself: Because I have a crazy imagination.
I hear things go bump in the night and then I'm too freaked out to go to sleep. And when it's not your own house, there are all sorts of strange noises. Especially when that house is on an acre of land up against a hillside and the dogs bark at every tumbling leaf.
Thankfully, this house is also in a pretty safe neighborhood and the noises I'm hearing are probably branches rustling against the tarp outside or the pool filter switching to a new gear.
And now it's time to try to turn off my imagination and make sure I have my husband on speed dial...