Our 5-year old gas cooktop has one burner that will occasionally spark as if it is trying to light. This happens when no one is in the kitchen and all burners are turned off. It is very random. Sometimes I don't hear it all day and right now it is sparking every few minutes. The burner doesn't light b/c the gas is not on. All other operations of the cooktop are normal and the burners do light when we turn the knobs.

I read elsewhere that this might be caused if the burner is wet. This is not the case. I cleaned the cooktop one week ago and all parts should be dry by now.

What could be causing this and how do we fix it? Thanks for your help.