I didn't get notified of these new messages, just saw them.
To ensure that nobody's drive is getting more wear than necessary, I've changed the autosave to happen every 60 seconds instead. After investigating it, there doesn't seem to be a consensus whether or not frequent reading and writing wears down drives. I will use a similar autosave interval for future games, and let the player manually save as well, to ensure a good user experience.
A differential save wouldn't really make a difference, the save file is already miniscule as is and only uses a tiny fraction of a percentage of what a drive is capable of in terms of data throughput. I speculate spinning up and down is what is making the sounds.