Bf acts weird whenever I’m on my phone

Me and my bf have been together for a year now. It’s been a blast and we’ve been hanging out everyday. We’re not very social people especially since COVID started, so it’s just been me and him in our dorms on campus. He’s supportive, sweet, loving, funny (similar humor which is rare), patient. Whenever we are hanging out, when I just look at my phone, he looks back at me and starts bringing up random stuff. It’s become somewhat uncanny that literally if I’m just checking for a few mins (even if he’s doing homework), he’ll start talking and bringing up random trivia.

This one time when he was doing his homework and I was on my phone. He looked at me and gave a loud sigh saying how he was worried about his parents coming to see him. As he was drinking water, he was watching me then closed his eyes quick. It seemed almost fake as if he was trying to get my attention??

I asked him if he was okay regarding me texting and he said, “Yeah! It’s fine!” and seemed nonchalant about it but will continue later. I feel like something is wrong. We both have hyperactive brains and check our phones researching, which he understands (at least he says he is).

He says he’s fine with me hanging out with other people and that I have a life. I only hang out with a few of my roommates and occasionally friends I meet on campus.

When I’m depressed or struggling with something and want to be alone, he says I can take as much time away and that he’s always here for me if I need to talk about anything.

I’m just wondering about his behavior of me on my phone. Even if he says that he’s fine with it. Idk what to do. Am I overreacting? I know from this that I won’t be on my phone as much but he’s been doing the same now. I’m not sure.