Should I be worried?

My boyfriend has more female than male friends, and I can’t help but to feel jealous every time he interacts with some of them. I’ve noticed lately that he’s been snapchatting a few girls lately which would be fine if he wasn’t so secretive about it. When I notice a girls name come up in his notifications, he puts his phone face down so I can’t see or he turns away to check what the picture is. He does the same when replying to the picture, he’ll take a photo then turn away so I can’t see what he’s typing. I totally respect his privacy but it concerns me when he’s open with everything else but as soon as it comes to snapchatting girls, he hides away. He’s admitted he’s received flirty messages and a picture of a girl in a bath and he replies with smiley faces or just laughs to see their reaction, even though I tell him to ignore it. We’ve spoken about cheating and are both completely against it and he says he would never do that to me. Should I be worried or am I just being dramatic?