I'm completing a major renovation of a 50's ranch style home, which involved moving some of the gas lines. The plumber put a pressure gage on the gas line and it held the required 15 psi for 15 minutes to pass inspection. The gage was left on overnight and in a 12 hour period it dropped from 15 psi to 8 psi. While I've met the city inspection requirements, should I be worried there is some pressure loss, or is this normal for gas lines considering all it is steel pipe with joints, etc. I'm looking to know what is acceptable and safe. Thanks for any advice.