Gas line in contact with concrete - is this code compliant?
The only code I know around gas lines pertains to foundation walls/floor.   There it must be in a sleeve.   For this, it is certainly best practice (and actually easier to pour concrete with a sleeve).
This is really only an issue in your case if the gas line material is corrosive to water and may never be an issue at all if it is under something and never sees standing water.   What material is used for your lines?