My husband (32), myself (27) and our baby (5.5 months) were exposed to someone with hepatitis b over the weekend. we shared a house with this person. are we at risk?

Depends: This is a bloodborne disease. Exposures through shared needles/sexual intercourse would be the method of transfer. It is not transferred through casual contact.

Vaccinated?: In addition to Dr. Ferguson's answer, you and your baby may also have been vaccinated. You can check with your health-care providers. Depending on where you live, your baby should have had 2 of the 3 vaccinations of the Hepatitis B series. Also, be sure that this was Hepatitis B and not A...the answers would be different for A.