I’m not saying you have any ill will towards Japanese people or that you intended to be offensive. But those excuses wouldn’t fly if you casually used the n-word, and I’m saying that IME “Jap” approaches that level of offensiveness. Maybe that’s not as true in Canada as the US, but my advice stands.
I’ll check in with a mod to see if the board has an official position.
(FYI, I also advise against using the term as shorthand for Jewish American Princess, which is almost as offensive as the other two cases.)