Gravel Spread and Footings Poured

When I arrived at the site this morning, the "Stone Slinger" was in action.  They were spreading gravel under the footings and where the basement floor slab will be.  At some point during the day the footings were poured.  When I went back thru at the end of the day I could see concrete poking out from under the insulating blankets.  It was pretty cold today, so we're hoping the concrete sets before it can freeze.  Of course the temps around here would have to be 10 degrees below normal while the most critical part of our home is being done...