My dr did a random routine blood test of prothrombin time and inr. my prothrombin time was 10.3 and inr was 0.9. i'm healthy in my 30s and not on any medications. does my slow time mean i'm more prone to a stroke or a heart attack?

Some clinicians feel that a prothrombin time under 10 seconds could indicate that blood clots sooner than normal, others don't place much credence in that. In any event your blood clotted in good time. Have you had any personal or family history of clotting issues like unexplained phlebitis? If not, I wouldn't be concerned unless you're taking oral contraceptives and/or smoke.