younger brother likes me

So for the past few months (about 3) my younger brothers have been acting weird around me, constantly taking off his shirt, fixing his hair, licking his lips, putting pillows on his lap, and I’ve also heard him agree when his friend says something like he has a hot sister. When he was younger (age difference between us is 6 years) he would always try to peek at me in the bathroom but I always thought it was just childish curiosity. One day I was sitting with him in the living room and on his phone I saw him literally looking at my Instagram pictures and zooming in on my boobs, of course I didn’t say anything because what were you supposed to say there? but I can’t stop thinking about it.

I’ve caught him masturbating a few times, more than once just on the couch or in the kitchen, each time he seemed less embarrassed and more excited, I’m pretty sure the kid likes me but maybe I’m overreacting? do you have any opinions on this?

Update: So based on what some people have said and my own desires I decided to tease him, an hour ago I was sitting alone in the living room (his bedroom door is in the living room so if he came out he could see me on the couch) and I started masturbating with my hand down my shorts while talking on the phone. I was hoping he would come out of his room and be hard enough for me to see it and maybe confess his feelings when I asked him why he was hard or come to sit on the couch with me. Unfortunately things didn’t go as planned so when he didn’t come out I started talking louder, moaning softly and moving my fingers so I could hear it. For a moment I thought he just didn’t notice until I looked down his door where to my surprise his phone was pointed right at me. He didn’t notice me looking at him but I can safely say I finished very quickly after that.