Sometimes my spells smart cast without having the smart cast activated

I dunno , since the last patch it sometimes happens that my skills either go off like they would have been smart casted, either my spells cancel themselves without me pressing the right mouse button to actually cancel them.

It's so annoying that it can sometimes make you miss important skillshots, like amumu`s q etc.

• EDIT :

Apparently this happens because on normal cast at least, the spells won't cancel when you press the right click anymore, like it did in the past patches, since the latest patch, the spell only cancels after you release the right click

** If anyone wants to reproduce this, try it in a custom game with champions that use skillshots, like Ziggs in my example. So press q, now the blue range indicator should appear . Now press left mouse button and hold it. Now press right button. The spell would have canceled right when you pressed the right mouse button in the past, but now it will only cancel after you release the right mouse button. And if you release the left mouse button first, the spell would just go off**