Died while running a node, but then resurrected with one heart!
So this is a new one for me.
I was running a level (L8 Energon Optimus, Medium difficulty, one of the new "river" nodes) and I died.
So after my "corpse" was retrieved by Astrotrain I got the standard "Unlucky" message, zero pigs, and the coins I'd earned during the run (no bonus).
When I returned to the map, instead of being required to recharge from zero, I still had one heart remaining and I could have restarted right away if I wanted to.
Weird.