is there any reason you can think of that would cause an artifact to occur on only one side of the model, but not the other? even with all the work being symmetrical

It's not uncommon for that to happen. Not sure why exactly, but my guess is that dynamic topology's mesh generation isn't 100% symmetrical. At which point you can use the "Symmetrize" button in sculpt mode's tool panel (when sculpting with dynamic topology) to return to perfect symmetry.