Self-rolling weight plate in a basement gym

There's this one incident in a basement gym where I worked out when I was about 15-16. I went there with friends, the place was as authentic as it gets: an old basement in a museum in a park, exercise machines welded together from whatever was on hand. The gym was run by a guy named Sasha, a former heavyweight athlete, he was 55. The basement constantly had all sorts of sounds, knocking and water gurgling, because the pipes were always dripping. One evening my friend and I came in together. The gym was empty, even the lamps were dimmer than usual. We started warming up, and then my buddy noticed that one of the weight plates suddenly rolled off on its own. And not just randomly, but purposefully – toward the center of the gym. We looked at each other, but didn't say anything; saying I was fucking stunned doesn't even cover it.

When we later told the guy about it, he was like, "Yeah, it's an old basement, all sorts of things happen. The main thing is, don't touch anything in the far corner, better not to go there."

What he meant by that, I never figured out.