[pikeselectric]

Good morning to all, this is Casandra with Pike's Electric. Noticed the thread and at the suggestion of Kenswing, I am happy to chime in.
If the post light is on its own, dedicated, breaker, and buried at the correct level, then there will be no GFCI outlet/receptacle associated.
If the post light was wired on to a circuit combined with other items (garage, irrigation, etc.) when the home was built, more than likely there will be a GFCI outlet/receptacle in the garage somewhere that provides GFCI protection to the entire string/circuit.
Also worth mentioning, if you have an outlet on your post light, it MUST be GFCI protected. Either a GFCI outlet itself, a GFCI outlet the post light comes off of, OR a GFCI breaker in the panel. Anyone installing outlets on post lights not GFCI protected is illegal and unsafe.
Hope this helps.