she floated the bag for about an hour then released them.
That is most likely the problem. SW
animals need to adjust to a few water chemistry parameters, not just temperature. A drip acclimation works great, and is easy to do, at achieving this. Here is a link describing the procedure- http://www.aquariumadvice.com/articl...q=2&fldAuto=18
Has the tank been cycled properly? Have the water parameters been checked to be certain evrything is good?