DWCook: I wouldn't worry about it. It's not so much whether the information you posted in your OP was "right" or "wrong", it's more about how you deal with being "corrected" after posting some "bad" information. I can assure you that everyone has, at some point, posted incorrect or inaccurate information themselves. And from what I've seen, you seemed to very humbly accept the fact that you were wrong. In other words, no harm, no foul.
Anyway, as has already been pointed out, as long as a person is at least 21 years old and otherwise lawfully entitled to possess a firearm, that person may lawfully possess concealable firearms (note that "concealable firearms" have their own legal definition under Missouri law - not to be confused with a "rifle" or "shotgun"), in the passenger compartment of a motor vehicle, without a permit of any kind in the State of Missouri. The LEO who harassed you about your "loaded .45", provided it was post August 28, 2003, was simply WRONG.