I'm curious why some people are suggesting a chimney cleaning. If the chimney was previously burning a gas insert, then it should be pretty clean, right? I suppose whatever was there before the gas insert may have left some crud if the flue wasn't cleaned, but certainly a quick look from the bottom and the top could determine if it needs a sweep.
That's true but since it was previously a woodburning fireplace it should be at least inspected to make sure it was cleaned properly before the gas insert was put in. At the same time, the sweep can check if the chimney is still sound and whether there are potential problems regarding the install.