High probability it may be the fuel. Gas dispensed from a diesel pump is not unknown or a gas component in the diesel. Especially if you think you smell it. Take a whiff of the fuel tank with the cap off.

May be simple to drive a car other than the ones you are having issues with back to the station and take a sample of the fuel and smell it. Or extract some from one of your two cars. I would tend to not drive them until I was pretty certain there was not gas involved or another undesirable component in the diesel fuel. Gas would be the most likely contaminate. You can also consider giving the station a phone call. Unfortunatly some will lie or may not be aware. You can damage the engines remember if gas is there. Depends on the percentage of it I suppose. Two cars at the same time on the same fuel is almost a certainty.