Confused - long post

I told my "boyfriend" or the guy I'm dating about this older man at my work. He's like 67 I think. But he's very flirty and brings me stuff. I told my guy that I wanted to stop accepting stuff (the old guy will bring me coffee or tea in the morning) because I think it'll make him think he can get something in return. My guy asked if he had asked for anything back so far and I told him "just a date here and there" and my guy asked what I said. Now, this is where I got awkward, not because I said anything wrong, I told the older gentleman I had a boyfriend.

But because, Last time I brought up being official or being more than friends he never really finalized anything. SO, when he asked I was nervous to tell him I told people I had a boyfriend because I didn't want him to be uncomfortable. I ended up mumbling and told him I told the guy I was seeing someone.

Like 20 minutes later I couldn't take it anymore because I felt like I lied so I said "hey when I said that, if people ask me out, I tell them I'm in a relationship". And then I said "but if that's not ok I can stop". He said "no you can do that I just wanted to know what you said" and I said "I said just that" and he said "ok because you could go on a date with someone and not tell me some people think that's ok" and I said "I don't think that's an option, I would never, would you?" And he said no like it was a stupid question. But now I feel like I made him insecure or question me. I don't want that. He hasn't made anything official but we are dating for sure and I practically live at his house. Did I do wrong? Should I clear it up by saying "look, yesterday I was awkward because I thought you might be upset that I said I was in a relationship. I hope you know that I only want to be with you" or should I leave it? He seemed to be a little bothered by it and I don't want to lose him. But also, if he was really bothered or wanted to be official why wouldn't he say "no you're my girlfriend" right then?