That's definitely some kind of clue. The theme of the book is from a detective series where the protagonist is trying to catch people who are cheating casinos. From the description:
"Tony Valentine has a gift for grift: He can walk into a casino and spot a cheater across a crowded floor. A man who still uses pay phones and won’t spend more than a buck for coffee, Tony has protected Atlantic City gambling palaces for twenty years and learned every trick of the trade—until a new one blows him away."