The spot is colder for some reason. Some deduction, testing, experimentation, and analysis might suggest why.
I personally think the alien/dog/llama/deer had something to do with it, perhaps something related to marking it's area.
Or if there was sun the day before, the last thing shading the spot could contribute to the heat retained in the surrounding concrete even hours later.
Another possibility is more insulation directly under the patch. The ground temperature a few feet down is equal to the average temperature area over the year. (We use this geothermal heat to keep the automatic livestock waterer from freezing.) No way to know how much heat is there since you live in an undisclosed location. A spot slightly more insulated can prevent heat from below from warming one spot as much as another. It wouldn't take much - a few tenths of a degree could make a difference. For example, a patch of drier gravel/sand containing more air could prevent ground heat from warming that spot compared to the same but wetter surrounding material, perhaps wetter due to water entering from the sides or from below. You could try profiling the area with an IR thermometer but would have to be clever about it. Set up monitoring cameras and track similar snow events to look for similarities (be sure to duplicate the last thing shading the spot.) Drill test holes for temperature monitors. Or get a backhoe and dig up the drive to inspect what's underneath. How much is this bothering you?
Or just move south and never think about it again.
JKJ