"Hanging out"

Chelsea
I have been seeing a wonderful man for the last month and a half. I literally don't have a bad thing to say about him. We've been making plans to take trips together, he's met my Mom and several of my friends, and he's surprised me by buying us concert tickets to a show we both want to see. Several of his friends have expressed to me completely unsolicited in public when we've all been hanging out together how enamored he is with me and that they've noticed how happy he is recently. I'm falling very hard and very fast for him. He is recently divorced, and I am very aware of the reasons why. He has been very open and honest about telling me about what happened with his now ex-wife, without me even asking. 
Now, for the wtf moment. Last night when we were out having drinks and looking at a map of a bourbon tour we want to go to in Kentucky in April (that we are in the planning stages of) at one of my regular spots I go to where I live, a random guy approached us and began talking to us. Almost immediately, the guy asked us if we were dating. 
The following is what is causing my mental and emotional tailspin today. 
Before I could even respond to the guy's question, the man I'm seeing smiles at me and responds to the question with, "We're hanging out". Then looks at me and asks, "for like a month or so right?", to which I just awkwardly smiled and said, "yeah". 
I don't know what to think. His response to this question that was asked by a person we don't even know is throwing me through a loop! Is this REALLY what he thinks because he certainly doesn't treat me like we're just "hanging out".
Any thoughts, opinions, advice would be so appreciated. I really don't know what to think or if I should talk to him about what he said.