Would a hepatitis b vaccine be needed for a person who is hepbs ag positive who later becomes hepbs ag negative?

Possibly: If, upon becoming HBsAG negative, you also become hbsab positive, then vaccination is unnecessary. However, some people can clear hb without forming protective antibody (hbsab), in which case a vaccination series would be recommended.

Probably not but...: Needs more information. The individual who recovers acute hepatitis b infection will have anti-hbs(antibody against heb bs antigen), hb core antibody with negative hbs ag.