Also a Brit here. I used to get annoyed, but eventually I think it seeped into my system as a different language as you put it. About 2 years ago I had a colleague get very angry with me for writing code analogous to:
Color colour = new Color();
To me, it makes perfect sense, and tbh didn't realise I was even doing it. I definitely endorse everyone standardising on American spelling though, now its been pointed out to me.