Expanding is a good sign. If they expelled all their water and shriveled up, that would be a bad sign. If they continuously reach up, you may want to consider moving them so they have better light. If they consistently do not expand properly, they may have too much light. By consistently, I mean over several weeks, not a day or two. Mine don't react well to being stung, so keep them well away from corals with sweepers...like hammers, torches, frogspawn, etc.