Answer:
Mr. Cunningham took a while to respond to Scout's presence and question because he was there to support the men who were trying to 'scare' Atticus from representing the black man, Tom Robinson. He did not want to be associated with the very man they were trying to threaten and also he was taken aback by the way Scout was talking so casually about her association with his son at school.
Explanation:
Harper Lee's "To Kill A Mockingbird" revolves around the story of the Finch family and their society where they lived, dealing with the racism prevalent during that time. The residents of Maycomb are presented to us by our narrator Jean Louis "Scout" Finch, the youngest member among the whole characters.
The town of Maycomb was rife with racism with some supporting it while some seemed indifferent about it. Amidst all that, the ra pe case of Tom Robinson represented by Atticus Finch became the talk of the town, who seemed to blame the black man for advancing towards a young white girl. Chapter 15 shows Atticus guarding Tom before the trial when Scout and Jem followed him to the town center. There, they saw a group of men approaching their father who was calmly reading a newspaper.
In her 'want' to help/ protect her father, Scout went out from her hiding place and addressed the crowd, among whom she saw Mr. Cunningham, the father of her classmate Walter Cunningham. She then began to ask about his legal matters, much to the surprise of everyone. Mr. Cunningham took a while to respond to the little girl mainly because he was 'anxious' about being connected to the Finch family among his group of 'opposers' of Atticus representing a black man. Maybe he did not want to be known to associate with them while trying to act responsibly. Also, Scout’s casual “matter-of-fact” approach, asking about his son left him surprised and also somewhat guilty of trying to be rough with/ before an innocent child like Scout.