What's the small habit you notice in everyone now, that you never saw before?

I spent the weekend watching a six-year-old grip a pencil like it was a tiny spear, and I realised I can't unsee the way people hold things anymore — pens, mugs, door handles. It's like once you start paying attention to hands, you see everyone's whole history in them. What's the thing you started noticing in strangers that you can't stop seeing now?