I was fighting a hoard of drowns and randomly got 3 hearts of absorption. The affect had no time limit, and didn't even show particles. It just permanently stayed there and then i eventually lost it from damage. I had a totem of undying in my hand, but I didn't die, and the totem of undying wasn't consumed. Im thinking that the game registered as me dying for some reason and applied the affects in an improper way.

Edit: I still have two of the 3 original hearts of the random absorption. Its not going away with out me taking damage so yes, they are permanent.