Is this stupid to be upset about?

So last night my husband and I were laying in bed trying to go to sleep and his Facebook messenger goes off (it was after midnight ) and he was like wtf? Well he opens it and it’s this girl he was friends with from church before him and I met. We’ve only been together a year and married for 4 months now. So he’s known her for years. Well he did the talk to text to message her back and I’ve read their conversations and I know they are nothing more than friends. But the thought of him pretty much waking up to answer her back at midnight didn’t sit well with me. I told him I didn’t think it was appropriate for a married man to be texting another woman at midnight. 😒 am I over exaggerating or what?