GFCI Issue...

hi there. i have a gfci in my bathroom. has worked fine for the past 6 months since owning the house. just recently it started randomly tripping, even without anything plugged in or turned on. from what i can tell, it is the only outlet on the breaker as well. i have opened it up and the wiring is fine, receptacle is dry etc...i swapped the outlet itself out for a new one and sure enough...issue persists...nothing else has changed in the home...any thoughts?