Should I be worried ??

So I found a deleted picture of my husband's coworker on his phone . He told me that he's been texting her because they're friends. She sent him a picture of herself so he sends one back when she does. That's happened several times, but not all the time . He says he doesn't remember why he saved the picture or why he deleted it . I didn't even know they were "friends" because he deleted his texts from her . I didn't know they talked outside of work. Should I be worried with all the sneakiness of deleteing things ? Girls don't send pictures to guys unless they want that guy to think they're pretty or attractive . And he saved it . And sends some back. I don't even get pictures of him that often MAYBE once a month if I'm lucky and I send him some all the time . He says he wasn't flirting but I'm just so suspicious .....