I found this from a Don Casey article that was linked at the bottom, its a little reassurance.
" Except on radical race boats, keels rarely fall off. The reason is that a huge safety factor is nearly always designed into the attachment system. Nevin’s Rule calls for one square inch of bolt section for every 1,500 pounds of ballast. Both galvanized steel and bronze have tensile strengths of around 60,000 pounds per square inch, so if a builder follows this rule, the bolts attaching a 4,500 pound keel are capable of supporting 180,000 pounds—a margin of safety of 40 to 1. Of course, the static load increases with heel, and we can only guess at the dynamic loads, but in a recreational boat neither is likely to test or even approach such bolt strength."
Keel Bolt Concerns