Is Receiving Hepatitis B Vaccine Additional Dose Instead Of Pentaxim Vaccine For My Baby After Three Shots Of Hexaxim A Concern?

Hello my pediatrician has suggested me to execute the pentaxim vaccine at 18 months ( as my baby already had 3 shots of hexaxim) but today when I went to pediatrician for pentaxim he gave hexaxim shot in place of pentaxim . As we are worried that additional dose of hepatitis b may hamper his health.help needed pls.