Veigar / Yasuo bug. Yasuo 'e' through event horizon.

I finally played veigar again today, and i got Yasuo as matchup. Sadly, it didnt go as i expected :( i didnt know that Yasuo could use his 'e' through event horizon. When it comes to his ultimate i knew it was possible to go through (teleport, in or out of event horizon), but not that he could go in and out with his e. I put up my event horizon around my minions, when he was coming against me. Oboooi did i get shocked when he then went in and out on other side... did some serious damage on me, then back through the wall again... WTF is this really possible or did i just discovered a bug???

Well... i dont wanna play that matchup again before i can read in any patch that this is fixed / nerfed.