I pride myself on having polite babies. I used to hear it a lot when Bianca was a baby--how polite she was with her please and thank you(s). I taught them by saying please and thank you to them; they likewise learn to be polite. It's been a bit rough with Portia. She started saying "thank you" early on but then turned to saying "welcome" every time she needed to say thank you. We understood what she meant. She finally went back to saying thank you. But she doesn't just say thank you, she says, "Thank you much." It reminded me that the word "very" is actually superfluous. We don't really need to use it as often as we do.
It also reminded me of this quote by Mark Twain that I have listed on my goodreads profile: "Substitute 'damn' every time you're inclined to write 'very;' your editor will delete it and the writing will be just as it should be."
Maybe she's a step ahead. She's cutting out the superfluous word before anyone need tell her. I should be grateful she's not saying damn. That wouldn't be very polite, now would it?