Scrolling on mouse moves crosshairs up and down

When scrolling between items your crosshairs move up and down which can be annoying when fighting mobs. I am on a Mac which may affect the bug. I enjoy Minecraft a bunch, and this bug isn't game breaking, just annoying. I've downgraded to 1.5.2, and I can scroll freely without the crosshairs jiggling up and down. If this is a new feature please add a way to turn it off . Good Day