Save yourself some heart burn and first determine if an appliance plugged into one of the outlets, supplied by the GFCI is causing the nuisance tripping. Turn off the GFCI then determine which outlets are off. Unplug all devices from those outlets. Next turn the breaker on and wait to see if it trips. Moisture in an outlet can cause nuisance tripping. If the breaker does trip then replacing the GFCI may not solve the problem. If the breaker does not trip plug each device into the outlets that were connected to the GFCI. Eventually as you are plugging in each device, one device will cause the breaker to trip. That device probably has some leakage current that exceeds the leakage rating of the GFCI usually around 5mA.
I have a GFCI outlet in my bathroom that trips off occasionally. It's mounted in the wall right next to the vent stack, which had a leaky flashing. When it rained, a small amount of water trickled down the vent pipe and got into the outlet box, causing it to trip.