Clearly Madoka is not used to compliments. Fëanor can see it in every stage of her startled expression. It's sad but also there's little pleasure in praising someone who's used to be complimented. Better she's not one of those.
Yet Fëanor, not for the first time, wonders what kind of world, or rather worlds, all those children were taken from.

"There's a mirror over there. You can go and look for yourself," he says with a smile.

If he ever had a daughter he most probably would have spoiled her terribly.