Beer Caps from Beer Bottles

Okay this is a strange question, but I am sitting wondering if this may be the cause of my cat twitching. My cat loves to play with beer caps from beer bottles. She loves the sound of them against the floor and loves to bring them to us and have us toss them and she will fetch them and bring them back.

She's been doing this since she was a kitten. But I'm wondering if this could cause her to twitch - or am I just be over cautious.

Why would it cause her to twitch?
Zissou has a massive collection of them hidden all over the place, as they are also her favorite toy.

Are you concerned about the beer on them or the aluminum?

I might not be understanding, but why would a bottle cap be the cause of your cat twitching?

I guess I was concerned about the aluminum. But maybe I am being over cautious.

Tks,

Could be her exitement also