Confused About a Student's Behavior

So you know how sometimes you just can't figure someone out? Yeah, that’s been on my mind lately. I've had this one student in my class who used to be so quiet and reserved, always working hard but not really engaging with others much at all. But over the past couple of weeks, they’ve become incredibly chatty during group projects, cracking jokes left and right, and even helping classmates out more than before. It’s like someone flipped a switch in them or something. This change has made me wonder if maybe I just wasn’t connecting with them earlier, or if there was some kind of underlying stress or problem that they’re dealing with now but found a way to cope with it through socializing and being more extroverted. Or maybe they had a major confidence boost from something outside school? But the thought of missing out on helping someone who needed it just because I didn’t know how to reach them at first... That’s what’s been bothering me, you see. It’s not that I’m worried about anything bad happening or think there's a problem now. Just that sometimes we miss seeing things clearly when people change so suddenly. Anyway, this whole thing has had me second-guessing myself as a teacher for days. Maybe I should reach out to them and just ask if everything’s okay? Or maybe leave it alone because who knows what they want from their teachers anyway. Gah, why does everyone have to be such an enigma sometimes?