Dear Jeff:
After only two episodes it is difficult to tell you what could be happening, mostly because there are so many things that could cause one-sided head pain. For instance, cluster migraine, hemicrania cephalgia, tumor, collagen-vascular disease, occipital migraine, infection, toxins, etc. I would see if it persists, changes in area, pain changes in character, and the like. If it persists for a few weeks, then I would recommend seeing your physician for more testing.
Sincerely,
CCF Neuro MD