Why did Dev become suspicious when the Sanyasi returned to Dahanu after only a month?

Dev became suspicious because the Sanyasi returned much earlier than he had been advised. Chapter 40 recounts that Dev had specifically told the Sanyasi to come back after two to four months, as another collection was currently active. When Dev saw the Sanyasi getting out of a tonga in town just a month later, he felt doubtful. He wondered to his son if the Sanyasi had forgotten their previous conversation or was ignoring the instructions given. This premature return was the primary source of Dev's suspicion and made him question the Sanyasi's intentions before they even spoke again.