Is this a known bug? J4

[Gameplay] - Champions, items, and game systems, etc

Playing SoloQ Ranked, and I got J4 ulted under tower. Thought for sure that I was dead, but I somehow managed to walk out of his ult?.. Why does this happen? It's kind of huge, especially if it occurs in ranked competitive play. Will not be playing Jarvan until this bug is resolved for sure.

Link to the video that shows the event: http://www.twitch.tv/teromin/c/5229933

It is the highlight titled "What just happened.. Ok."