Hang on,
you just changed your OIL filter, but were draining fuel out of it? that doesnt make sense,
There should be oil in the oil filter that would be normal.

If you have made a typo and you have changed the fuel filter, and found oil in there, it would be worth looking into what is going down the return line back into the fuel tank from the engine, as you may find it is oil contaminated, either that or someone has been adding oil to the fuel at some point which would be a little odd.