cheating??

should I be worried that the girl my boyfriend kissed a few months back ( I found out literally like a month ago but I forgave him) called him while we were together?? We’ve been together for a year now and he was just like he hasn’t been talking to her and he really doesn’t know why shes calling but.. idk he blocked her number in front of me but still lol and he tried to like distract me from the fact that she called cus he KNEW it pissed me off. So what should I do??? I wanted him to answer the phone and put it on speaker but he jus let it ring and acted like he doesnt know why she was calling