Would y'all be okay with your significant other adding random girls back on Snapchat if they added him first?

So last night I noticed a girl message my boyfriend on Snapchat and ask him who it was, because I ain't never seen her before. He said, oh, it was just some girl added me on here so I was like let me see what she says at first he was like no and kept asking me why until I kept pestering him to show me and when he did she was asking if he was single and saying they should talk. I asked him why he's adding girls on Snapchat if he doesn't know them and he just said he adds everyone back. Now all I keep thinking is, if I wasn't there, would he have told her he was single.. Like why hide that. My boyfriends never gave me reason to not trust him, but lately, he's been a little weird with his phone, so I've been naturally suspicious.