chapter 4 kinda retconned the first one with it implying he didn't actually see her but just hear her and imagined what was happening for those wondering about that
No it didnt? Thats a different moment.
He even says shes "doing it AGAIN" in chapter 1 after he explicitly looks over the border, showing hes seen this before.
Then in ch4 he assumes shes doing it yet again this time too but was mistaken, but its only this time where he assumed wrong not the first. Nothing whatsoever implies the scene we saw in ch1 was in his head. Like...nothing at all.
He only feels bad he assumed wrong in
ch4, but that doesnt...retcon what happened before at all.