Re: Lawyers help please....
If the position is non-union, go to your state's Wage and Hour Division (department of Labor) and file a complaint. Better yet - just inform the employer that you will be doing so. Employers hate Wage and Hour reviews as they will look beyond the one instance with your wife and look for a pattern that can be very, very costly.
The NLRB would refer her to the State or Federal Wage and Hour people.
By the way - not a lawyer here, just a humble HR person.
Nothing to see here. Please disperse.