Ben, I had the same problem. A few weeks from new, the two nuts holding my van in place came right off. It's the so called 'locking nuts' they use are useless. I bet you have the same as mine as CFR and Powrflite are made by the same company i think. What I do now is use a spring washer between the washer and nut to add friction, and then cover the end of the bolt in rubber sealer. They haven't come loose since.
I'm not a fan of american made :
