Went for ob check up and it says im positive for hep b surface ab. Should I be worried?

Not necessarily. Your body makes hep b surface antibody in response to the hepatitis b vaccine. It can also make it to the hepatitis b virus. If you've been vaccinated, it's more likely to be due to the first reason. If you're still concerned though, a test for hep b surface antigen and a liver function panel should clear things up. Most likely, they were checking your immunity status.
No. Need not worry. That just mean you are protected. You have the antibody against hepatitis b!