My fiancé is getting pictures of other women?

Recently I sent a picture to my fiancé of me wearing new underwear (I know crazy huh) but it was more of a close up picture without my back and face in it. He asked if it was Sydney.... Apparently he thought it was his friend Shane sending him a picture of a girl that he's been talking to. Should I be concerned that his friends feel comfortable sharing pictures of other girls with him or the fact that instead of replying "dude, don't send me pictures of other girls" he responded with a "humm is that Sydney or another one?". Please help.