Anchor bolts are extremely important fastener that holds a sill plate to the foundation by being grouted into a CMU. The entire building is anchored to the foundation with these fasteners. What happens if the grouted CMU cell cracks or the bolts crack the grout around them during the installation of the mudsill? Drill a 2" hole near the location of the loose bolt and fill with masonry cement to secure the bolt. Don't ignore foundation cracks, they can compromise more than just the block!!