Does your husband have close girl friends??

I was doing my homework on my husbands computer, when an I message popped up on my husbands computer. It was a text saying just hey from a girl responding to his text that he sent at 2 in the morning on his way to work. I asked him about it and he said it was just his friend. However as his wife I feel I should know when he is talking to other girls. I just feel a little weird about it that he would text a girl at 2 in the morning. What do yall think?????