Gameplay Viktor's Q vs. towers

The last few games i noticed something that happens when Viktor Q's a minion and the uses his "improved" basic attack against a tower. It allows the attack to hit the tower multiple times until the spell ran out of time. Its not registering that your using the improved basic but you still do massive amounts of damage. Considering that a built Viktor has lichbane and an ungodly amount of ap you can burst through a tower at a ridiculous pace.