Good Luck/Bad Luck Cancel Each Other Out?

Last night when I came home a black cat streaked across my path. Fortunately I didn’t run over it with my car. But as I was walking up the back steps, a ladybug plopped onto the front of my blouse. So I don’t get good luck, I guess. The good luck (ladybug) just canceled out the bad luck (the black cat)? Sigh.