What specific circumstances led to Dev's 'delusion' and failure to recognize Sai Baba as the Sanyasi?

Dev's failure to recognize the Sanyasi as Sai Baba stemmed from a prior encounter that created a 'delusion' in his mind. Chapter 40 explains that before Dev had even invited Baba to the Udyapan, this same Sanyasi had visited him to collect funds for cow protection. Because this first meeting was for a completely different purpose, when the Sanyasi returned on the day of the feast, Dev's mind was fixed on the idea that he was just a guest. Dev later lamented this, realizing his vision was confused because the Sanyasi's first arrival happened before the invitation to Sai was extended, making it difficult to connect the two events.