I have seen American spellings in communications sent out to parents by teachers in an English school.

Word spellchecker? Browser? People don't know so they trust them, and don't know to install the right lexicon. My Firefox steadfastly refused to spell in English. But you can install English (United Kingdom) or remove it. But despite moving American down (not default) but you cannot remove it.

As I understand it, gotten was common in one area in the UK, I think West Country, and that is how it has gotten to America. I would say - think Mayflower, but reality there is not strictly West Country. And doesn't it come naturally to a tutophone?