Firefighter here. Anytime there is a smell of gas it has to be concerning.
Did the firefighter's or Atco smell gas too? It might have dissipated from the time you called them to when they arrived. I wouldn't hesitate to call them again if you smell it now.
Edit: I see photon asked the same question. Natural gas is actually odourless, what you smell is mercaptan which is added to the gas....if anyone cares
