As someone from a trashy family and have been in my fair share of bar fights I think you are looking too much into this.

Your husband isnt a fighter. He probably doesnt want to talk about it. It is always over something stupid when people are drinking. If it was something serious the cops would have been called. 99% something really stupid and someone who likes to fight hit him. he probably threw a couple punches back. It was broken up.

My suggestion is let it go. he will get drunk some time and tell you what happened.

My friend got punched randomly once at a bar. he was upset about it for years. I think he is still embarrassed it happened. Some people dont think violence is as funny as others.