Responses
she used to be kind of neglected if you remember. When mehen was too busy and didn't realize and all. Maybe they think she learnt it somehow then? If not then maybe it's because her playing wasn't flawless (as FL said)? Or they're just used to child geniuses.
A child that they have been cared since she was born suddenly - magically - know how to play a violin out of nowhere and they don't question it?