I am finishing up my home build and am installing a 9.5 gpm rheem tankless water heater. I did all of the plumbing and electrical in the home with the exception of the main LP lines. The plumber that ran the lines used flexible gas line called trac-pipe. From the little I know about gas lines is that they should be grounded? I have not grounded this line yet but intend to do so. What has me concerned is the fact that I got a little jolt when I grabbed the yellow flex line on the water heater and the iron gas line running up from main flex line. The water heater is not plugged in. Where could I be picking up a current on my LP line and is grounding the only precaution I need to take? I didn't notice the current while hooking up the range or gas dryer. Thanks for any input.