Change the signature. You are still the same as before. If he asks about the time or alludes to it, you can explain it to him. Forget it. You didn't say anything about him anyway. You don't have to be sad. My feet are afraid of crooked shoes. You don't get along well anyway.

If you're sure he saw it, Why don't you explain to him and take this opportunity to make up with him and get along well? After all, we are classmates. If you all go out into the society, you will know how valuable the feelings between classmates are.