I do the exact same thing. Back in highschool people used to point it out or look at me weird or assume I was upset. My boyfriend asks me "What's wrong?" and I respond with "Uhh...nothing?"
I've done it for as long as I can remember and it feels like it relaxes my nerves.
Yeah, I'm in my early twenties and my mom is in her sixties. A friend of mine is in her mid twenties and her parents are both in their sixties, too. Some people wait longer to have kids for various reasons. Luckily, my mom barely knows how to open Chrome, so at least I don't have to worry about her getting addicted to TikTok lmao.