My boyfriend asked me "hypothetically" if I would say yes if he proposed.. is it really a hypothetical question though?

We were going for a walk and he asked me. I asked him where the question came from and he said it was just a hypothetical question, like if I would rather eat nothing but broccoli for the rest of my life or drink nothing but tea (not exactly but you get the picture). I definitely don't think it's a hypothetical question of the same caliber though. I told him that I would say yes if he asked, but I don't care about getting married in general. A little background info: we've been together for 4 years, have been living together for 3, and are considered common-law (we even did our taxes together for the first time this year). Seriously though, I know we've been together for a long time but I'm happy and I don't feel that a title/document/ring is necessary for me to be committed to him. I guess I'm not very traditional. He's "proposed" to me before when we first started dating because he didn't have citizenship in our country, but I said no because if I were to get married I didn't want it to be for citizenship, and I knew he could get it through work (which he did). After that he stopped asking me but has brought up marriage/kids a few times. Thoughts?