No, I'm a scavenger, it happens on all aoe attacks quite often, on revenants, viles or barons, I suspect that the damage is applied after knockback so it hits nothing. Might also have something to do with dodging from hellrunner.
UPD: I took some hits for research, does seem happen about half of the time with hellrunner*3. Seems to be combination of dodging and knockback.