急求！面签通过，但是网上状态显示行政审查？

上午面签通过，没给蓝色单子，问签证官说通过了，下午网上状态是：Your visa case is currently undergoing necessary administrative processing. This processing can take several weeks. Please follow any instructions provided by the Consular Officer at the time of your interview. If further information is needed, you will be contacted. If your visa application is approved, it will be processed and mailed/available within two business days.这是怎么回事