Caitlyn Passive + Ivern W + Hitting a Turret

I was playing Caitlyn the other day and there was an Ivern in the game. On Caitlyn, hitting a turret or other structure stacks your passive, but once it reaches max stacks it stays there because you can't headshot something that doesn't really have a head (duh). Caitlyn gets double stacks for autos fired from brush and this works with Ivern brush too. You could not, prior to the introduction of Ivern, attack a turret or any other map structure from brush. The bug I encountered was this: I was in Ivern brush hitting a turret. My passive reached max stacks, and every auto after that my passive would alternate between max stacks and max stacks - 1. I imagine this bug occurs with Zz'rot Portal Void Gates too and is much more common there, though I have not tested it. I guess it isn't exactly very high priority to fix this bug, but it is a bug nonetheless.