Welcome to Android Central! Look carefully at the front-facing camera--do you see any condensation on the inside of the glass? If the seal was broken due to the crack, it's possible that some moisture got in and is now causing condensation to form. If you do see some, you might consider the old Ziploc bag with uncooked rice trick (or even better, use some of those desiccant packets that come with so many products). Put the phone in the bag with the desiccant for 24 hrs, seal it, and maybe that excess moisture will be absorbed.