Stirling's intonation is off. Overall, she's not a very good technical violinst at all. I'll give her credit that she has the whole pixie-enthusiasm thing down to an art though.
I'm pretty sure what he said (or at last meant to say) was "...with a little Peter Dinklage" - meaning "a bit of Peter Dinklage". Poor choice of words to be sure, but I don't think he was actually making a short-joke.