Besides his preference for seedless grapes, was there another reason Dharamsee didn't want to eat the ones from Baba?

Yes, there was another significant reason for his hesitation. While he did have a personal dislike for grapes with seeds, a more practical concern was a health-related one. As Chapter 35 explicitly mentions, 'the doctor had forbidden him to eat grapes without washing them.' He was in a difficult position because he felt it was inappropriate to wash the grapes himself in that holy setting, but he also felt it would be disrespectful to reject what Baba was offering him. This conflict between his doctor's advice and his reverence for the situation caused him considerable inner turmoil.