You are right to be cautious
I had a buy to let. The tenant complained about gas smell and called Transco who promptly capped the supply on the meter. I had had teh landlords CP12 a few weeks before and called the gas chap back. I watched his manometer which dropped not a mm.
I can only conclude the dozy tenent left the 20 year old hob without flame safety device on low and the idiot Transco employee either did not turn this off OR he was unaware there was a central heating boiler with a pilot and thermocouple. I can think of no other explaination unless his rubber hose had a pinhole
neadless to say I complained to Transco but to no avail but may be effective if he makes a habit of this
There was never another smell of gas thereafter
HTH Phil;