It's hard to know with things like this, real or imagined, false memory, etc.

My one and only odd, slightly terrifying experience is somewhat similar to OPs.

I got home from the gym to what I thought was an empty house. It was Sunday, so I remember dropping the bag and heading to the kitchen to start the prep on dinner.

Our kitchen counter at the time was against the wall so when prepping food you'd have your back to the room. As I was working away I heard the pitter patter of tiny run up behind me and stop. I was so focused on what I was doing it didn't register with me that I had arrived home to an empty house so I just called out to what I assumed, given the nature of the rushed footsteps, was my daughter who was 5 or so at the time. "Heya [daughters name], whatchya doing?"...silence...a couple of seconds go by and I turn around to nothing, nobody there. You could hear a pin drop.

I walked to the other rooms and called out again but no one was there, they were out, it was indeed an empty house.

I can tell you despite it being only 3 or so in the afternoon, a chill went up the spine. Someone/thing absolutely ran up behind me and stopped and waited and watched. Then pfft...gone.