Why did Dev become suspicious when the Sanyasi returned to Dahanu much sooner than expected?

Dev became suspicious because the Sanyasi returned after only about a month, despite Dev having explicitly told him to come back after two to four months. The source text from Chapter 40 highlights Dev's doubt when he saw the Sanyasi alighting from a tonga. Dev wondered why he had returned so early and whether he had forgotten their previous conversation. The reason for the initial delay was a conflicting fundraising effort in the town, so the Sanyasi's premature return made Dev question his motives and whether he was disregarding the instructions he had been given.