Should the title of a short story have a comma after it if it is the subject of a sentence?
Solution 1:
I believe the professor is confusing dialogue with a citation. In prose, the correct form would be something like:
"I am answering a question on Stack Exchange," said Ian Atkin.
The AP Manual doesn't implicitly have a response, but in explaining the rules, uses the following:
Jean-Luc Godard’s film “Masculin Feminin” would be cited as “Masculine Feminine.”
Solution 2:
There is absolutely no reason for using a comma after a title unless the structure of the sentence dictates otherwise.