Regulators breathe....you will sometimes hear them if you are around
the regulator when a large load starts or stops. The smell of gas is
probably from diffusion thru the diaphragm mixing with the air that
sits up in the regulator body between "breaths"...
That jackass gas man should have explained this to you.
If it still is bothering you call the gas company back and tell them
you dont trust the judgement of the first "tech"...or just tell them
you are really worried and would PLEASE like a second opinion.