Regardless of his weird bi-polar attitude, he's still so freaking adorable! I can't wait for the later chapters when they really start to bond together as friends!
This time the young master does not understand it, his vision has improved but the protagonist has not done anything in particular.
What reason is there to get angry if he is better now?
My guess is that his feelings for her are undoing the curse. However, he suspects her of having played part in the casting curse since it's becoming undone near her. Prob worried about trusting her since she might have alterior motives for being nice to him.