Hi Sara,
He may have lost interest.
He has looked and smiled at you in the past without any reaction from you.
Indeed, he may be frustrated with your body language. In not looking at him because you are shy, he may have gotten the impression that you don’t like him.
Asking him a question about the course activity was not enough to convince him that you like him. After all, you could ask anyone that question.
That was most likely the reason why he did not reply to your question and went off in some other direction.
As of now, it appears that he has lost interest.