Well, anything is possible, but I've never seen a breaker fail that way (and I've seen more than my share of bad breakers). More likely you are using a cheap DVM to determine if there is voltage present or not. They are notorious for returning bad readings when no voltage is present. You need a 120/240 volt circuit tester such as http://www.drillspot.com/products/73...Voltage_Tester or a analog multimeter if you can find one.
Also, your main disconnect is probably at your meter.