Whenever a patient has considerable swelling of the face/neck., etc its always a good idea to take them to the ER. Its always better to err on the side of caution especially when you dont know what the cause for their swelling is. Plus, at hospitals they are equipped and knowledgable of this sort of thing that they know what to do if it would suddenly get worse. Paul is right (as usual ) . It could be from an infection which could be a major problem to someone who is recovering from a major surgery.

Best wishes and please let us know how you make out!