So apparently the Queen flies back to her starting point and regains all her health (but not all her shields) when she drops to 10% health, or when the you've been in the instance more than 25 minutes, or at random intervals consistent across all instances.
I just quit a hive space elite where a three man team of myself in a mirror sovvie, a tac in an Atrox, and a tac in a temporal destroyer got her down to 10% after the rest of the team quitting.
And then someone in instance 25 started flipping out in chat, followed by instance 13, followed by instance 20, followed by instance 21, followed by a bunch of other instances.
And I was like "lol what?" and then she just warped out and healed to full, and I started flipping out in zone chat too.