The Cable Guy (1996)

Answer: If we're to assume it to be an intentional addition to their dialogue, and not just a minor continuity error, maybe it was just Steven's way of handling Chip's uncomfortable initiation of the topic? I can buy Steven not understanding what Chip was talking about when he said "I set em up, you knock em down" without much context to set up that convo. But once Chip says he juiced her up and helped get her back, it seems like Steven gets what he's hinting at. The way he turns away and sort of flees while asking "how did you know we're back together?" (to me) seems a little more like an effort to avoid acknowledging what Chip did, and a little less like him genuinely not knowing Chip's involvement. As if he was in denial and didn't want to openly accept the situation for what it was. That's just my guess anyway. I hope it sounds like a fair enough point and not like something I'm looking too deeply into. Never really gave that moment in the film a second thought until reading the question.