To fix a problem correctly you need to know the cause. If you can't reproduce the problem you're unlikely to know the cause. For instance: Maybe the ground connection in the pedestal is marginal and the small physical movement caused by resetting the GFCI caused it to be "fixed". Problems that fix themselves almost always return. The only pro-active thing that makes sense is the "shotgun" approach of verifying that the connections inside the pedestal are good, and that your shore core connection from the pin on the plug to the RV frame is good.