Delayed kill minion

Multiple players saw a minion which refused to die with what appeared to be about 10 hp and was attacked by 5 differently timed attacks over 5 seconds. Not a single user issue. Should not have survived through 5 seconds, my auto attacks are precious gems to me.

Just finished the game, ARAM. Melee minion. Happened near first tower encounter, ~2-3 min into game