Ex girlfriend concerns..

This might be long so I’m sorry but I’ve been seeing someone for 5 months (still very new I know) but we have been together just about every single day since the day we met and the other night I was over at his place like any other night and he’s showing me something on his phone.. at that moment he’s getting alerts on Snapchat from his ex.. it seemed he tried to lock it so I couldn’t see but it was too late so shit was weird the rest of the night. But right after it happened he started being overly lovey which made me wonder if he was trying to get confirmation whether I saw it or not. The next day I brought up how I feel like he’s not being completely honest with me and he explained the reason he was extra lovey is being he knew I saw and wanted to make sure I knew he didn’t care what she has to say and that I’m all he wants. He says that she randomly reaches out to him for random shit but he never responds and there’s nothing to worry about. He also said he’s not one to “block” anybody because it would cause drama but that’s the only social media he has her on which is weird to me considering it’s the most “sneaky” social account in my opinion. It’s been bugging me for days and I don’t feel like myself and I feel self conscious. I have been so confident about us and him up until now. Am I stressing for nothing? Is this something I should talk to him about again? Help :(