Gas leak

I just had the stove/oven converted from propane to natural gas and now I can smell gas when stove and oven are off. All connections and orifices have been checked and rechecked and there are no leaks. The smell seems to be coming from the oven. My suspicions now turns to the oven safety switch malfunctioning and allowing a small amount of gas to seep by. Would this be a logical assumption at this point or might the problem more likely lie elsewhere?