When I first read the excerpt I didn't have much sympathy for them. After reading the full article it seems the husband got a new full time job and they shifted off Obamacare part way through the year. In essence they are paying back subsidies taken while on the healthcare with money they made when they got off the plan. They are paying a price for the ACA only having a one year look to determine the subsidy.
The same thing could happen in reverse.