Tryndamere ult bug [GamePlay]

During a match in treeline, I believe I encountered a bug. I was tryndamere, and there was a Heimerdinger. His ult was on his turret, and as i was about to die by the giant turret, I pressed my ult. As the sound for Tryndamere's ult was going off, I died, and it put my ult on cooldown. I know my ult wasn't running out as i died it finished yelling. It was only leveled up one time as I was only level 10. The Heimerdinger was only level 12 so it wasn't a full build game. I had smite, flash for summoners, and for my items: Stalker's blade:chilling smite, Bligewater Cutlass, Recurve bow, Boots of speed. Heimer's spells: ignite, flash. his items: Wooglet's Witchcap, 2 doran's ring Sorcerer's Shoes, and Amplifying Tome.

This has only happened to me once, as i've only played it once with that match up.