My Little Brother Ruined My School Supplies Daydreaming About Me as a Teacher!

So last week was back-to-school supply shopping time and I bought some new folders, pens, highlighters. Yeah, yeah, basic stuff for my classes but also fun for me because I like to keep everything nice and organized. On Sunday I thought it'd be a good idea to set up all my school stuff since the first day of school is tomorrow. My little brother Tommy, who's in fifth grade, came into my room looking like he had something on his mind. 'Hey big bro,' he says with this look on his face that makes me think I'm about to be accused of eating his snacks again. But no! 'I have a project for you and school tomorrow!' Now before you say anything, yes it's early August in Ohio, and yes my room is stuffy. But hear him out. 'See,' he says with this huge grin on his face, 'if I was your student, what would you teach me first?' He looks so excited and maybe a little hopeful that I start to feel bad for being such an older brother. So we play along for a bit. We go through subjects, talk about all the fun stuff I'll learn as a teacher. But then he does something weird. He takes out his notebook and starts scribbling down notes on me! 'Now write this,' he says, pointing to my folders and pens, 'Mr. [My Name], he likes orange folders best.' He keeps going about how I like pencils for math class but highlighters for history. And then the kicker? 'I'm gonna make a poster with your picture!' It's supposed to be cute that he wants me as his teacher but there’s also this nagging worry in my head. After all, can you blame him for thinking teachers should be nice and organized like me or is it weird for someone so young to think about school stuff before even getting a schedule? I mean, what if other kids start acting like that too? So here's the thing: Is it normal to worry about your little brother being obsessed with you as his teacher when he’s just looking up to older siblings in general? Should I be proud of him for thinking about school early or is this a red flag and I should talk to our parents? Am I overreacting?