Yas windwall agro?

While playing yasuo in a recent game I had something odd happen at two points in the game, while charging against the tower I used my windwall to block ranged champions ziggs and kaisa from hitting me while i was hitting the tower, then suddenly as they tried to hit me the tower put its attention towards me and started hitting me, there were still minions and i did not attack anyone but the tower with simple auto attacks and had my windwall up. Doesnt seem right