That sort of turns around the context to positive for me. If he'd only said it in return to maybe a "why do you like me" then I would say he just likes the fact that you like him. But I think it being a reassurance says it's more like, you give him the time of day. Which is cute. Obviously beyond that I don't know what he's like but in that particular context, I wouldn't take it as a red flag. But yeah just talk it out, it seems like maybe you've got some of your own insecurities about the relationship or yourself- not trying to be judgemental, of course, it's totally normal!