I had Sears' home service out to look at the unit, and the tech said it's part of the new (worse) design, something about the way two plastic lines of differing inside diameters are joined together and the pressure difference. I specifically asked if this could cause wear problems down the line with the compressor or other parts of the cooling system and he said "no".
Not for nothing, but I don't believe the guy. After 40 years of refrigerators whose only sound is the fan, I have to put up with a refrigerator that knocks like my car's engine when I forget to put premium gas in the tank? That's either a crock of poo, or the dumbest damned design idea.
Is the guy right? Does anyone have experience with new 'fridges making these noises? Am I going to have to suck it up and put up with hearing the noise from my bedroom in the middle of the night? Or should I call a local (reliable) appliance repair place and have them check it out?