Has anyone had someone use your Lic. to solicit work with outyou knowing about it??

If we answer that question "Yes" then at some point we knew about it, right?

Its illegal to use someone else's license to contract. If you have a document that another person has generated with your license number on it, then by all means report them to your local Contractor's Licensing Board. They take that stuff very seriously and will shut them down pronto.