I'm very sorry. I don't know if that's what caused it , but it is a possibility. Was the substrate moist and was there water in the bowl when you came back? Could your place of work have experienced an unexpected drop or jump in temperature? I only ask because you mentioned she appeared dried out. A necropsy could be performed, but this can be a bit complicated.
http://www.dendroboard.com/forum/gen...#/topics/22090
That link to an old dendroboard thread has more info on necropsies if you'd like to read more, but it may not be a possibility at this point. I don't know. I really wish I had more info for you. I also own a pixie, and they're awesome frogs. I'm sorry for your loss. I hope you can figure out what happened.