Symptom
After upgrade to 6.2.12 , show run shows an extra config for hsrp
priority 100 forwarding-threshold lower 1 upper 100?
Workaround
Reconfigure the hsrp sessions.
Version up from 6.2(12) might be able to make these type of priority config.
"priority 255 forwarding-threshold lower 0 upper 255"
Issuing just "priority PRIORITY_VALUE" resolves this situation.