The goodnight text

My SO gets mad when I fall asleep and forget to message him goodnight. He says that the little things add up to be big issues later... I don't see it like that, I see it as me making an honest "mistake" or just falling asleep because I'm really tired, I really don't do it that often. Am I just being one sided and it really does matter? Or should it really not be that big of a deal?