Secretly Loving My Little Brother's Stuff

I've always looked out for my little brother Sam ever since we were kids. Now that I'm in college and he's still at home, the dynamic has changed a bit. One thing I never thought would happen is how much I enjoy his stuff. Like when he borrows one of my graphic tees or takes my favorite notebook to school, it's so annoying! But secretly, I kind of like having things back that are now 'his.' The other day, I found myself hanging onto a sweater of his for weeks before giving it back. And just this morning, I stole a pair of headphones from him to use during a study session. It feels weird but also strangely satisfying. Am I the only older sibling who does this? Should I be worried about my little brother noticing or thinking differently of me if he finds out? What should I do?