My thought on that is that when the Prodigal Son returned home his father hosted a huge party to celebrate. On Sunday my soul had much to celebrate as I had been back to church for one month and took communion again.
I got to thinking that this page is a joyful place, a happy spot in my world and life and that the cake represents a celebration. My return to my faith is cause for celebration, and being alive in Christ is a celebration. So why not a happy button/image to go along with that line of thinking?