It wouldn't be over a walk. It would be over his behavior. He was unkind and rude.

If this is the first time he's ever done something like this, it's worth talking to him about, after he's had a chance to cool off from whatever was bugging him that day. "I felt very hurt and confused by your behavior on that walk. Can you explain to me what was going on? I'd like to understand and I'd like for us to talk about how we can avoid similar situations in the future"

If he's rude and snippy frequently, and it is something you can't accept and he won't change, now is probably a good time to cut your losses and move on.

Mind you, it's possible that he has grown tired of maintaining the courtship behavior that attracted you to him, and is starting to revert to his normal self as infatuation fades and real life sets in. If you start to see this behavior more frequently, that is probably what is happening. The real him is showing up.