A few weeks ago, I heard what sounded like a quiet clicking sound coming from inside my MacBook Pro. This has been recurring 1-2 times every week since then. It clicks only once at a time. It's a 2019 MacBook Pro 13 inch. My first thought was whether there might be issue with the hard drive, but the machine has an SSD, so there shouldn't be any moving parts, if I understand correctly? Do you have any experiences or ideas about what might be causing the sound?