Egg Grill A Robin Laid 4 Eggs In Our Grill A Week Ago, All Of A Sudden There Are 5. Where Did This Extra Egg Come From?

A robin laid 4 eggs in our grill a week ago, all of a sudden there are 5. Where did this extra egg come from? - egg grill

I also worry about the heat that comes into the net? It is made of metal and the temperatures were in the 70s lately. I think a car can heat to get there.