Weird after preschool

My 2.5 year old started preschool today. He is going half day three times a week. I am a stay at home mom so he is used to me all day but I do a lot of play dates so he is social with other kids. He loves the park and will always find someone to play with. He talks a lot and is just out going. Today after preschool he was quiet because he was tired. After his nap I tried to ask him about preschool and he wouldn’t answer. My husband tried as well and he just wouldn’t talk about it. We tried to ask him simple questions and he just kept ignoring it. He’s just been kind of off since he has been home. The teacher said he had a great day. Am I overthinking this or do I need to ask the teacher the next

Time I see her?