I saw this a few years ago. If I remember correctly, the Sawstop blade is actually part of a sensor system enclosed in a box underneath the table. The blade brake engages when something (your finger) comes in contact with the metal blade and completes a circuit. From what I understand, they had problems with some units cutting wood that has absorbed to much water and tripping the continuity sensors.
Its a great product, dont get me wrong, but I dont think spending $69+ on a new blade each time the saw senses a wet piece of wood is worth it.