Are you sure that it didn't originate from VAFB? I spent 30+ years in the Army and depending on where I was stationed I might have to get the appropriate state tag. I spent two years at Fort Stewart. It was not my permanent duty station. I was there TDY (Temporary Duty). The state of Georgia (and USAA) gave me a bunch a lot of trouble because I kept my North Carolina tags (and insurance). Maybe an MP (not sure what you call them in the Air Force) saw you car on post for several days, thought you should have California plates and decided to make a report. Or maybe not.