My boyfriends "girl Bestfriend"

So I've been with my boyfriend for awhile now and for about a month he has had this girl Bestfriend named Brooke. Brooke is 14 me and my boyfriend are 17+ and they have never met before in person ( as far as I know) but today I ran into her and met her for the first time. So I took a picture with her and sent it to him and he screenshot it. I was barley in the picture and he wanted to keep it. I asked why and he got mad and said it's already deleted. Should I be aware? I mean I trust him enough to forget about it but it seems sketchy. Any opinions?