Breaks

I just had the Cylinders, shoes, and pads replaced on the rear breaks of my 1998 KIA Sportage. They also re-sized the drums and removed the air from the break line. The car is running fine, but when I was driving the other day I knoticed a little odor from the new breaks. The conditions that day were really bad, a lot of snow on the ground and slippery. My parents say there is nothing to worry about, that they are "buring" through the film on the breaks. A problem that occured on my parents explorer that had breaks done the same day. Any thoughts.