Kinda sounds like the fan more than the gimbal. The gimbal tends to make a gentle clicky sort of noise as it moves, on a lot of birds the ribbon cable scrapes in various places and causes this noise.
If it's in warranty, I'd see about getting it replaced. If it's not, and the camera otherwise stabilises itself and works correctly in flight I wouldn't worry about it. At least not until / if it fails completely... The fan is a cheap part, but the cable is glued to one of the camera boards and can be annoying to change...