No I don't think your being too precious about it. I'm the same. Christ, I was one of those kids that would be DYING for a drink over at a mates place and wouldn't ask lol I didn't want to 'trouble' anyone. I think she's just let her shyness REALLY get the better of her kwim? Some kids are just ridiculously shy around other people. Which, as you said is no excuse. But maybe you could even say something to her as well as your DSS and explain why it upsets you so that way she learns?