Something I thought about, one time.

I had lived at 15 Tietje Drive for years, as a child. I rode my bike up and down the adjacent stretch that was Concord Dr. more times then anyone could care to count, and my feet beat their way in the mornings when I'd walked to school. I had spent interminable days locked out doors - ostensibly because it was a nice day outside, but perhaps because it afforded my parents ample time away from my brother and I's incessant bickering, back-biting, and outright physical combat.

Basically, I knew my neighborhood well. I lived in it.

One day, I noticed a speed limit sign just off the curb coming into the neighborhood.
25 MPH.
I'd never, ever noticed it before.

The unexpected and the new are the roots of both delight and fear, but while novelty spawns interest, something acting other then it should spawns disquiet.

There was nothing unusual about the sign. It was made of metal and planted quite deep. My parents insisted that it had been there as long as I had (and indeed, it's there today) and ventured a kind of startled amusement that I had never noticed. "That boy," they said, bemused. "would not know if his head were missing." But for me, it had never been there. I stood unnerved and a little bewildered. How could I have missed this sign for so long? But, well, it was just a sign. There's no twist to this story. I became as used to it as anyone else, now that I had learned to see it.

Familiarity breeds contempt, as they say. And how right they are to say it.

There's a lesson here. I'd like you to imagine something.
Your home is quiet and you're alone, enjoying a peaceful night in who knows how long but it's getting late and you've had a long day. You decide to run a bath before bed and the water's hot enough to fog mirrors and slick panes. Finally, you're done and wrapped in a towel, you open your bathroom door. 

Across the room from you is a door you've never noticed before.

It's motel-room white, with a plain but serviceable looking doorknob. It doesn't really fit with your home's decor, but aside from the fact that you've never remembered seeing it before, there's nothing particularly unusual about it. You've lived here for months - maybe years. The landlord showed you around. You checked every possible room before you moved in. You even remember tapping the walls to check insulation.

There's nobody around to ask. You realize you're getting cold, standing around in your towel.

What do you do?

You get dressed for bed, with your eye on the door. Do you knock on it? It's silly. What if someone answered? You examine the doorknob. It has a key hole. There's no light coming from underneath. There's no sound on the other side. You try the knob. Gingerly. Gently.

It catches. It's locked. You're alone in your home at night, with an unfamiliar locked door. Think about that for a little bit.

At first, it's disquieting. But you spend an uneventful night, worried about it before your housemate comes home.
"Oh, that?" they say. "Yeah, it's just a closet. I don't know why it's locked." they say, unlocking what appears to be a shoddily painted but normal looking closet. "You don't remember it? It's been here since we moved in." You can swear otherwise, but they're adamant. After all, closets don't just appear. You store coats in there, Christmas gifts. You chuckle to yourself about how you never saw it before and you gave yourself quite a fright. It's very easy to ignore something your sense and mind tell you when it defies the norm.

It's fine, really, until one night you're alone and you hear the doorknob turn behind you.