Did You Notice THIS Mistake in Full House?

In the episode “Just One of the Guys”, D.J. accidentally says something nonsensical to her cousin Steve, who comes by for a visit, “Hey Steve, you want to go ice skating tomorrow?” But when he says he can't because he has plans. D.J. then says, “Oh, well we can go tomorrow!”, which she knows isn't possible since he just said he already has plans.