"But I didn't notice you switching! I didn't see you acting differently!!" You did, actually, you just phrased it as:
"You're quieter than usual."
"Are you feeling okay?"
"Quite the chatterbox today, aren't you?"
"But you said (x opinion) earlier!"
"You don't need to use big words, you can talk like you normally do."
"You're too old to play pretend."
"I thought you liked/didn't like (x)?"
"What's the occasion for this sudden fanciness/attention to detail?"
"When did you gain such an attitude?"
"You're such a strange child."
"Your demeanor changed."
"It's like you see (x) and a switch is flipped."
"Don't act like you're a little kid."
"What's with the sudden accent?"
"Are you alright?"
"Talking like a Victorian child now, are you?"
"You're so... quirky."
Just because you didn't know the word for what was going on doesn't mean it didn't happen. You just substituted what you didn't know with what you saw as the most logical conclusion (which isn't necessarily a bad thing, it's just when you continue to press your assumption even when told what the reality is that you become rude). It's not your fault that you missed the signs, but the signs were there, and we'd like to have some acknowledgement of that.
