Sounds to me like a normal hdd while working and since you've been running hdtune it makes perfect sense. Man I ran mostly ssd or m.2 nowadays and hearing those little hdd farts bring so many memories :_) Anyway If you start to hear more of squeak/screech or if ur drive will be making any noise while idle that would be the point to start worrying. Other sign of potencial fail would be increadibly slow transfer (minute or so to copy/move a single pic for example) or corrupted/disappearing files.