Basically, I was thinking that the creators had an in-world explanation for Toph thinking that Katara "had a secret thing with Haru" . Namely, Katara was embarassed around Haru when Toph first met him. The show's viewers see her blush, which obviously Toph can't see. But according to wikipedia, she probably can detect the general emotional states of people, as an extrapolation of her li-detecting abilities. If so, she may simply have misplaced the cause of the emotion(like a lot of viewers have in the past), and her comment may be taken as an example of series continuity. I would like to know if anyone else has considered this possibility, abd whether I could mention under series continuity for part 1 of the finale.