Not as tacky as referring to yourself as “doctor” in the context of a medical discussion when your field has nothing to do with medicine whatsoever.
It doesn’t invalidate your opinion, but it’s worth being aware of your own cultural context when making judgements.
Mind you, calling yourself anything which isn't explicitly self deprecating gets you mocked in NZ.
Is this a Philosopher's Stone/Sorcerer's Stone situation where someone published an Americanized edition and that's what I have?