Hmm, if that's happening, it must require other conditions, I wasn't able to repro it in a couple of dozen tries.
It may be worth noting the little life meters displayed on units only have so many sprites (nine to be exact) associated with them. Sometimes a tiny amount of damage won't move them down to the next sprite, and Punish in particular among "smite" type abilities does relatively low damage.
I'll put it on the regular pre-release build testing rotation for a bit though and see if I manage to knock it loose in later testing. If you come up with any other information about a repro case, please let me know.
Thanks for the report!