The mystery of how a chain of gas stations was able to sell below the market rate has gotten a bit more interesting.

Freedom Fuel Network, an upstart chain of gas stations mostly in the Philadelphia area, got a lot of attention — and praise from President Donald Trump — for selling gasoline at about 50 cents a gallon less than the local market in July. At the time, gas prices were up more than 30% from a year earlier.

The company had long remained mum as to how it was able to sell gasoline for so much cheaper than competitors or how long it intended to do so.

Now, there’s a lawsuit alleging that the company that bought the fuel for Freedom Fuel Network did not pay for $4 million worth of gasoline it purchased from a supplier last month.

The suit was filed on August 19 in US District Court in Eastern Pennsylvania by Manfield Oil Company of Gainesville, Georgia. The company’s attorney, Urs Broderick Furrer, told CNN that at least 1.12 million gallons of gas deliveries were made to at least 10 Freedom Fuel stations.