As I say it's just a curiosity, but how did you get to that comment? Diving through all the posts?
Maybe, just maybe, it is. Or someone linked your comment to someone's thread asking the same or related to the question.
By seeing your merit history welsh did gave you same amount of merit on old replies, maybe he's a fan of yours or a stalker? Kidding aside, I guess that's how a merit source do when someone often make quality posts.