Next time you go out with him — not next time you talk on the phone, but next time you see him face to face — ask him, without any judgment in your voice, what he meant. You can say something like, “You know, after we kissed, you said, ‘Don’t go falling in love with me,’ and I don’t know why, but that stayed with me. What did you really mean?”
I have a feeling it was a throwaway line, and didn’t mean anything except that he was nervous and excited by the kiss, and felt like he had to fill the silence and said something dumb. But you have a right to get some clarification on whether he’s trying to tell you he’s not available for love or not.
I don’t think it’s a big deal, but it’s a good idea to [i]lightly[/i] get clarity.