If the concrete mix was not air-entrained, it would also behave this way. Air-entrainment is produced by a chemical additive that creates microscopic air bubbles in the concrete that will allow it to withstand the forces of freezing. If this is the case, continued low temperatures will probably produce more of the same.
Lastly, sometimes when a finisher is trying to place a hot load (concrete is too old) they have to work it too much to get it nicely finished. This overworking will drive the air-entrainment from the mix, and/or change the water/cement ratio significantly enough on the surface to cause this scaling.
The fix for this type of problem can sometimes be achieved with an overlay, or re-surfacing with polymer mixes such as Ardex CD or some MiraCoat products. This repair should be performed by the contractor at no cost to you (that's my opinion as a concrete contractor).