Looking at those pics, Todd, the corrosion appears to have started at the edge of the panels (behind the bumper cover and running board garnishes), and not affected by chipping or abrasion directly.

I suspect that the rust was already there when you got it, but the increased humidity in PEI combined with salty roads caused the rust to speed up a little.  Fredericton, being inland, tends to be colder and drier than coastal areas - for example Fredericton's relative humidity is currently 32% whereas Charlottetown's is 64%.  Humidity combined with road salt will accelerate corrosion, so it's quite possible that exposing the vehicle to PEI conditions just sped up what was already happening.  I'm just going by the photos, though, it may be a different story seeing it in person.

A little background info:

https://www.imoa.info/download_files/stainless-steel/DeicingSalt.pdf

"For corrosion to occur, a materials surface must be dampened by an electrolyte, which is a water solution that can conduct an electric current. There is a direct correlation between regular surface dampening of corrosive surface deposits and the corrosiveness of the environment. Moisture can come from rain, fog,or even humidity."

If you drive on gravel roads where they use Calcium Chloride or Magnesium Chloride to keep down the dust, it can have even greater effect:

"Salts influence corrosion rates in several ways. First, salt is hygroscopic, meaning it absorbs water from the air. This makes it possible for corrosion to occur at lower relative humidity level sand for longer periods of time than otherwise expected. Second,salt increases waters ability to carry a current and speeds up the corrosion process. Third, the chloride ions in salt can break down the protective oxide layer that forms on the surface of some metals. For example, aluminums otherwise protective oxide layeris damaged by salt exposure.Salt gradually begins to absorb water and forms a corrosive concentrated chloride solution when critical humidity and temperature level combinations are reached (See Table 2.)14It is at approximately these humidity levels that corrosion is most severe because the corrosive solution is most highly concentrated. When several salts with different critical humidity levels are combined,the temperature and humidity range at which corrosion can occur is broadened."