Thank you for all of your responses. The mystery remains, but there are many more factors to consider than I had before. I will continue my hand washing, will definitely consider washing my fabric before using because I never thought of what it could have been through before I got it. For some reason I have always thought of a folded three yard pack of fabric was neat and clean. It may look that way, but for some reason I now will wonder what adventures it had before I got it. I scrub the dickens out of produce, keep chicken as clean as a baby, and use Oxy for our laundry. There are just somethings that I have always considered clean, but still scrub as I'm sure all of you do as well.
The Machingers are still the best I've found so I'll just keep on washing them as part of my routine.