I have to agree, I think, Jimmy. Because of the first person narrative, especially. That's your characters voice, were seeing their thoughts and an American would think with their own spelling. I find this kind of thing hard - I wrote a short story set in an unnamed American city and had to think dumpster, not bin, sidewalk, not pavement. Though I ran it past two American bloggers and they thought it was okay. (One told me re dialogue, 'we just sound a lot lazier than Brits'. Not sure all Americans would agree, but that was his view!) You did the absolute right thing getting a an American to read it - could they help with some spelling, too?