Boyfriends Trip

My boyfriend and I have been together 5 years and lived together for 2. He's a good guy in general other than the occasional hiccups. He just informed me that he wants to go to Austin with his friends to hear a band for 3 days, one month after baby's born. Should I be mad or just let him have his fun? Is getting mad overreacting over something like that? Sometimes I don't know if it's the hormones making me go crazy or if I have a valid reason! Ugh pregnancy!