Just noticed a very faint electronic noise coming from the SSD in my 2015 15in rMBP. I only noticed it last night while working in a quite room, and don't recall ever hearing it before having had this laptop since 2015, but then I've mostly used the machine while outside of my home. This is what it sounds like: Not loud but noticeable from a normal sitting distance. Just wondering if this is indeed normal behavior like the video claims? Anyone else's machines making this noise? Thanks!