[@Loony] You just made me think of a really good point.  In the first episode Steven wants to activate his gem's ability and eventually does, but the circumstances had to be just right.  Garnet, Amethyst and Pearl's advice didn't seem to help much, but the episode established that every gem's ability has different ideal circumstances for it to activate, right?  Since Spinel was made to be a stealth gem, maybe it wouldn't be too unreasonable for me to say that the knowledge of her abilities just sort of clicked, because the circumstances were right?