I can report my K5 "occasionally" just decides that it should be remounted after being ejected from the computer. often ages afterwards.
possibly a change in charge level to maximum or something stupid?? but I've noticed it happen plenty of times to know it is a true "glitch".
It also -just now- refuses to use my wall charger currently (works fine on all other kindles) for no obvious reason. Might be going back to the shop.
Ooh, and I ran my k3 into the ground the other day accidentally for power. full shutdown job. the wall charger did manage to revive it after about an hour. Did have a few tense moments though
Ah power. what a joy