Should warfarin be continued for six months if pulmonary embolism as a result of ocp?

Yes. As dr. Milstone said, the recommendation is that someone take warfarin for at least 6 months after being diagnosed with a pe. After stopping the warfarin, there is recently published evidence that taking low dose Aspirin for two years can help to prevent your getting another blood clot.
Good question. National gudelines in the us typically recommend 6-12 months of blood thinner (anticoagulation) after a pulmonary embolism or deep vein thrombosis (leg clot) even if birth control pills are thought to be the cause.