I've had such a great relationship with this couple and the dog has been a sweetheart til now. She honestly seems to have developed a second personality. Anyone have any ideas what might be the real root of the situation?
I would ask them the exact same question adding something like "apart from the move can you think of anything else that may have caused this.....has anyone new been introduced to her...could someone be hitting her without your knowledge.....dogs respond to praise not punishment etc etc" that type of thing. Try dropping less than subtle hints that you've got a good idea why Holly is reacting like she is...

My other idea was to pin him up against the wall, punch him in the face and ask him how he likes it..................