This always bugged me too, I wanted to know what the situation was! They never explained it enough and I liked them as a couple. As for the Gippal's "Cid's little girl" thing I'm in favor of playful teasing. Rikku smiles and says "Hey, I have a name you know!" it seemed pretty flirtatious to me. Maybe in ten years they'll pop out a compilation of sequels and we'll know.