I'm hebs ag negative with a high anti hbs antibody from vaccination. This week's test was reported as hebs ag detected with anti hbs antibody of 513 miu/ml. Lft normal....Scared....Lab error?

Yes. That sounds like lab error. Your hbsab would provide immunity; i'm assuming yoru hbcab (core) is negative; i wouldn't worry, talk to your doctor about a retest if you are concerned, but even if you were infected, there is no reason for treatment at this time.