You are imagining things.
lol jk
You have accidentally created a sensor. Just great when that happens. It is likely interference.

It may be that you're getting enough capacitance to have an effect. You could trying swapping in some various small capacitors to see if you can achieve a similar effect.

You could even get one of those little variable capacitors used for radios — really old radios really used "air capacitors" — and then you can tune it to see if you can get a similar sound.

I found an interesting bend in a children's toy, and then realized that it still works even when the leads are just close to each other, but not physically touching. In fact, the sound is a bit different that way from when it's a physical connection. Has anyone run into something like this? I have no idea what could be causing it. Some kind of electromagnetic interference, maybe?

It creates a great sound, though, so I'm trying to figure out how to include it in the project and be able to control it in a more predictable way. Since I can't use a toggle (the two bend points wouldn't be far enough away), I was thinking I could use a couple of RCA jacks with some distance between them and just patch it, although I'm not sure that would work. Is there a better way to handle this kind of thing?