From the facts you present, if he stated his consent to the order as signed off by the special master then the only way he could change his mind would be to file a motion or petition for a rehearing. He would also have to provide some substantive reason for changing his mind.
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We don't have "masters" in New Jersey. I assume this was a hearing officer. He can change his mind at any time and file a motion with the court. I wouldn't worry about it until and unless it happens.
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