Is the house new? If so the builder might still be responsible for repairs. And yes, if there is moisture around the crack you need to have that looked at. You do not want to finish out a basement with moisture problems; you would just be closing in a place for the mold and rot to grow. Plus, if the crack is moisture related, it needs to be fixed and the source of the moisture needs to be determined and rectified as well. I just bought an older house with moisture related cracks in the basement that required professional repair and the installation of french drains outside to deal with the water / moisture issue that started the cracking in the first place.