A question for nitpicky readers

Just started reading The Three by Sarah Lotz.  Who is South African. (It matters--keep reading)

And almost stopped.  

And this is where I need your input.  So the first section of the book is in limited third-person narration about an American character.  And there were some things that immediately showed me that this was an American character in a book rather than an actual American and thereby pulled me right out of the story.

"She hoped there wouldn't be a queue for the bathroom."

"The time the stabiliser on the washing machine broke."

"She didn't want to die amongst strangers."

"She saw the rust on the other car's bonnet."

Trivial things, really, but they pulled me out of the book and almost made me give it up.  Am I overreacting here?  I mean, I suppose the Commonwealth English spelling of stabilizer I could overlook, but no American would think these other things, which, though they are in third person, are clearly supposed to be Pam's thoughts.  

It would have been just as distracting to me if she'd had a British character and the sentence said something like, "She laced up her sneakers, pulled on a sweater, and got in the elevator." 

So: does the author or editor have a professional responsibility to ensure that characters who speak different versions of English actually use those terms in the book?  Does the failure to do so indicate a lack of professionalism?  Am I too nitpicky? Why does this bug me so much?  

Any and all answers would be appreciated.