Just some minor inconveniences lately in exchange for being top dog in a manga with her name. A small price to pay. But yeah, there it is. The four leaf clover in Miyahara's hand signifies the fact that the odds are strongly in her favor, as if to drive this message home further to everyone.
I'd be surprised if Arima doesn't spill his spaghetti, drop the ball or flub anything while walking home with Yukihira. Because that's just how things have gone so far. Maybe Yukihira is unlucky after all. It's like 12-1 in Miyahara's favor right now.