Wait, so Seamus said: “Nearly headless? How can you be nearly headless”?

Bought the whole collection yesterday and Reading the books for the first time :)

Currently in the middle of the first book and it says seamus asked Sir Nicholas that phrase, not Hermione.

I wonder why would they purposely give that line to Hermione in the movies when Seamus was literally in the same room with them? Not that it matters much but it just seems weird to go out of your way to needlessly change some stuff