Is he cheating?

Sayge

My bf just got a instagram and he followed some webcam girls and sent flirty Dms to them. One said you were so sweet the other night ( that's what she said to him)I didnt read anymore of it. Another he told a girl she had perfect eyes.He doesn't know I read them. I told him to delete the the girls off his instagram and he did. I am still mad at him, but I am keeping it inside. Should I tell him or just let it go