Cheating

Catherine
I need some help from you all.
I have been dating my boyfriend for six months and he is absolutely the love of my life and my best friend. However, I am scared that he may have verbally cheated on me.
A week ago, his friends threw a party and this girl he used to go to high school with was there and then when she left, she was texting him all night. He told me this too so I know he wasn't trying to hide anything. I also know he finds her somewhat attractive because that night, he said, "yeah well she definitely didn't used to look like that in high school!"
Then, today I see that her conversation was deleted from his phone. Now, I see him just about everyday and I know he would definitely tell me if he physically cheated, but I can't help but wonder as to what I should do.
Should I confront him or wait until I notice this behavior again?