Did you candle before setting them? It's not quite hot enough yet to get early development in shipment in my opinion but I have had a chicken chick hatch on day 16 in the middle of summer because it was incubating in an insulated corner of the coop, so it can happen. Do you have a secondary calibrated thermometer? The temperature may have been a little higher in your incubator than the readout suggests or hot spots in the incubator.
This was my summer chick.
View attachment 2048202View attachment 2048203