My husband keeps searching up his ex on facebook

So me and my husband have been married for about 6 months but have known each other for about 12 years. I always wanted to be with him during those 12 years. I knew he was the one but we were young and it took him some growing up to do before we got serious. I’m now expecting our first child and have never had any doubts about him. Pregnancy has been hard between the sickness, fatigue, and hormones and I know I haven’t been the best wife I could have. He’s never been secretive and often leaves his phone around and sometimes I go through it, more of a just for fun thing instead of a suspicion thing. He knows I go through his phone on occasion. Well in the past couple days I went through it and saw he searched up his ex on Facebook. It really hurt my feelings as this certain ex is a sensitive subject for me because back when we were young he chose her over me. So when I saw that it really hurt. I googled similar situations and saw that a lot of people said it’s usually just a curiosity kinda thing. I’ve never had Facebook because social media has never been my thing. When I saw he looked her up it hurt but I decided to let it go and just try to start focusing on being a better wife by paying him extra attention, cooking, and everything. Everything has been great and I started feeling more assured. Well he left his phone out again and I looked through it honestly not expecting to find anything but to see that he’s been searching her numerous times. I guess I’m just wondering is this a normal thing? Are my hormones clouding my judgement? I’m in my 6 month of pregnancy so I’m feeling really insecure and he’s looked her up probably 4 times this past month. There’s no contact but still. How should I go forward with this? I don’t think I can just ignore it anymore.