I had a problem where the GFCI appeared to randomly trip in the early morning. Cause was located to a scratched wire in an outside outlet downstream. It was related to the dew in the morning.
I had another one that would randomly buzz. I thought the noise was from the nearby trash compactor and unplugged it. The GFCI then faulted later by arcing. I replaced it and when I looked inside it, you could see a damaged coil.
Steve
