Moving corals higher (or lower) can occasionally alter their color, especially if you notice the shift after moving them. Many times the new color can just happen in the new growth and as it keeps growing the inside heads that were outside heads will then change back to what you see in the middle part of the piece now. I hope that makes sense! You can move them a little lower if you like the other color better and see if it changes back. Whatever you decide to do, give the coral time to adjust and as little moving around as possible is best for the health of the coral