why does melinda think mr freeman is driving to fast ?

Mr. Freeman wastes no time leaving traffic behind him in the snowy weather, leading Melinda to believe he might possibly be driving too fast.

I watch the beer truck fade into the snowstorm in the side mirror. Part of me thinks maybe he is driving a bit too fast, what with all the snow, but the car is heavy and doesn't slip. The snow that had caked on my socks melts into my sneakers.