2006 Scion xB brake problem

I have a 2006 Scion xB with 196,000 miles on it. In the last 15,000 miles, it has developed a problem where the car, when it is just coming to a stop, will cease braking for a few inches before it catches again and stops. My (non-dealership) repair shop insists everything checks out and it does indeed stop every time. Anyone have any idea what is causing this unnerving behavior? Thanks in advance.