Alistar with Demolish (death)

I came across a bug where i was playing Alistar in a Normal 5v5 draft using the Demolish Rune. around about 25 - 30 min i died under tower, and demolish was on cooldown, but while i waiting to respawn demolish came off cooldown and proceeded to do its charge up thing on the tower WHILE I WAS DEAD, and then when i respawned demolish was on cooldown again. I dont know if this is intentional or not, and it is not a major issue but i just thought that i would let you know

Kind Regards - TheeSouthAfrican