I recently made a comment about how my daughter knows a phrase in Slovak: Jak sa maš? (How are you?). I know that most Slovak speakers would argue that the first word should be Ako instead of Jak.
There are two possible explanations (I think) for why my version is different. First, there are regional dialects in every language, so my Baba might have spoken non-standard Slovak. Second, she immigrated when she was quite young (and that was a very long time ago), and language evolves. My dad said the only word they used for bathroom really meant ‘outhouse’–but the Slovak that he learned was what was common among farmers at the turn of the 2oth century.
I know a professor who teaches French and German, but who has a Ph.D in Norwegian. She had studied Norwegian in the 1960’s, and the language has become a lot more informal since then. She said that when she speaks Norwegian, it’s like she is saying “My good sir”, instead of just “Excuse me”.