Also, where it becomes grey in my mind is yes glock hasn't released information that actually shows what a preban is or postban is (I know this is talked about often) and there are plenty of threads that show the differences. But, I don't have a bill of sale of course that shows I purchased this magazine before the ban. Reason being, I didn't. Could this be a problem?
That officer was a dillweed. You also have no obligation to prove a preban is preban. The state has to prove it’s not.
If you get jammed up for something (guns seized after a red flag/restraining order for whatever reason or use a gun in self defense and have your LTC pulled), then very possibly the police will charge you with an AWB violation for a “large capacity” magazine. LEOs and prosecutors just like to throw everything possible at people to leverage into a plea deal. Don’t talk and wait for your attorney. You’ll be fine because your preban is legal.