Final answer:
The minor conflict involves a man indirectly blackmailing the speaker for more money, leveraging his knowledge of a hidden door related to Mr. Frank.
Step-by-step explanation:
The minor conflict in this excerpt emerges from an interaction between the speaker and a man who initially asks about Mr. Frank and expresses a curiosity about a hidden door. Tension increases when the man, later on, demands a raise, which is an example of extortion driven by the knowledge he has about the secret associated with the bookcase and the door. This creates a subtle power struggle and ethical dilemma for the speaker, who must decide whether to accede to the demand for more money to keep the secret hidden.