T.G.
My daughter is about 27 months and had the same problem at about 20 - 24 months. She started taking later and shorter naps. Although I hadn't changed her daycare or anything else in her normal routine at home, things did change at daycare. My daycare provider does school runs, and in the summer time when she doesn't have the school runs. So even though you haven't made any changes other then the daycare, it could just be the variations from one daycare to the next.