GAMEPLAY - potential alistar bug

I have been playing a lot of Alistar, and I have begun to notice something out of place. I do not have evidence of it, but if Alistar dies near a structure (I've seen it only on turrets) while his passive is active, his passive will continue damaging the turret for as long as it would have had he been alive.

Steps I would use to recreate this:

1. use any ability on Alistar to trigger his passive
2. die, standing next to a turret
3. check for damage being dealt after death

I haven't died next to a turret enough to know if there are any more variables, these are my only current discoveries.