I think a good next step would be to chat with him and ask to tell you more about what he meant, ask in as neutral a way possible and respect his answers.
It could be that he’s saying he likes what you two have shared so far, and would like more.
If you’re lucky he’ll be able to articulate the facets of his admiration for you (really lucky, who’s good at that?). Could be he has thought about what he said to you and he might have a lot of detail to share – could be he’s in love with you, how do you feel about that?
Then again he might heard the line in a movie and was trying it out, innocently, with you because with whom else would he try it?
It’s at least a compliment, and a “shucks, thanks!” can encourage more of this positive feedback.