flashing light on water heater

I noticed the controller on my gas water heater flashing constantly today and there is a very, very slow drip of water coming out of the release valve. Its a five year old John Woods tank with a Robert Shaw controller. From searching the internet I found something about a "lock-out" function but not sure what that means.

I turned the electrical breaker off, then back on. The light turned off and the pilot immediately turned on and started to heat the water. What caused this to happen? Anything I need to be concerned about? Any insight would be greatly appreciated.

thanks.