I was thirteen, and it was one of the last summers I was spending a long time up at my grandparents' house. (They lived up in the north suburbs, in Brooklyn Park, and my folks and I lived in Omaha at the time.) I stayed in the basement bedroom where Grandpa kept his books and his stamps and everything. So one night I'd been reading, and I set my book and glasses on Grandpa's desk and turned out the light. I tossed and turned trying to get comfortable. And stopped.
There was the glowing outline of a door across the room.
There was no door to the room, just the door down to the basement. I was too old to believe in things like that. I rolled over and screwed my eyes tight shut. A few minutes later I checked again: glowing. Door. Yep.
No. No, I knew there was no such thing, no door there, I was seeing things, dreaming, reading fantasy novels too late at night. I rolled back over. I shut my eyes.
...And had to check again, because -- glowing portal! Come on. You can't go to sleep with a glowing portal in your room, no matter how tired you are.
I put my glasses on, and it was still there. I ventured across the room very slowly, expecting it to disappear any minute. I grabbed at my backpack just in case, not taking my eyes from the outlined light of the door. Just in case. If there was something. Going to get shoes from upstairs would take too long -- it might disappear -- but the backpack I could reach without looking away.
I put my hand out.
It was the door to the cedar closet. It wasn't used as a regular closet, just a storage closet, and so I usually forgot it was there. Grandma had retrieved something during the day and left the light on inside.
But the point of this story is not, ha ha, stupid kid, nothing ever happens. No, it's that to this day, I'm really, really glad that I was the sort of person who checked. I don't like either, "it must be something truly weird," or, "it can't be something truly weird," nearly so well as, "well, let's find out."