WF self heal helix cumulative?

Is it just my imagination or is WF’s healing mutation (220 HP in 10 seconds on a kill) cumulative? I soloed Rendain on advanced difficulty without losing a single life. I killed the smaller minions pretty quick with napalm and criticals, and it seemed that my health gaige would rise up to full in an instant, when killing several of them in quick succession.

That’s what it seems like to me but I haven’t gone out of my way to double check either.