Sounds like a little moisture in your tank has created some rust, or just some bad gas. That is the only thing I can think of to cause black goo in your filter. As far as the oil, newer cars have a sensor that wont let the engine start if there is not enough oil. As long as your car runs OK and you change the fuel filter again it might be OK. But I can't imagine it would cost a bunch for a shop to pressure test your fuel pump. PS Tell hubby to check you oil more often.