I have a question about the phrase "dismiss someone's concern"
Suppose the following is a paragraph that is from a recommendation letter:
I was worried about her performance due to the demanding nature of the curriculum and the fact summer session has a faster pace than regular semesters. But Michelle dismissed my concern by proving to be a person who is able to successfully develop plans and implement them.
Is "dismissed my concern" correct use in this context? I think dismiss is a negative word. I am looking for a better phrase to express the meaning