daycare behavior issues - they think he is autistic

My son will be 3 in January and currently goes to daycare three days a week and stays at our home two days a week. Those 2 days my mother-in-law comes over and watches him at our house. He has recently been having trouble at daycare... he won't listen to them, he screams at them, he slaps them in the face, runs away from them and refuses to take a nap. He rarely does most of this at home and has never slapped at me. At home he sleeps in a crib and goes to bed and nap just fine. For nap even if he doesn't sleep he stays in his bed and talks but never screams. As a bit of a background. He had been at daycare with this same arrangement until about a year ago and I lost my job so he was then at home with me and went to daycare 1 day a week or 1 day every 10 days or so. Then he started back with the 3 days at daycare and 2 days with my MIL about 1 1/2 month ago. The director called me today and told me she thinks we need to get him evaluated that he has behavioral issues and might be autistic. He, to me at least, exhibits none of the signs I read for autism and showed no signs at his 2 yr old dr visit. The dr is the opposite and typically tells me how bright he is. Am I just being a naive parent? What are your thoughts? ps i do have a call into the dr but she is out of the office today.