Yes, you do! But that is the wrong question. Mold is found in virtually ALL indoor environments, because as already mentioned it is a normal and necessary organism.
There are some specialized, high-tech environments that need to be absolutely mold-free but normal, healthy homes and businesses will always have some levels of certain molds found indoors. We just do NOT want most mold growing or producing indoors, which is often an indicator of moisture intrusion indoors, and at this point IS a problem that needs to be investigated and resolved.