50 states 50 rules. A Federal carry license would be nice. There are Federal transport laws (unloaded and locked up) but stops along the way as well final destinations gets many people in trouble.
In IN it is a license to carry a handgun. When an officer runs your driver's license the carry license will also pop up. If you call the desk sergeant and give him your name, it will pop up in the computer. The driver must have done something to catch the officers attention that he ran the guys plates and maybe being out of state was all it took. States seldom report that information to other states so I find that odd.
Unfortunately officers are not always as proficient with the firearm laws as they should be. Sometimes just being out of the norm is enough to end up facing the sidewalk. Just because it's legal does not always mean its smart.
MI and OH you have to declare, IN you don't. I normally had my carry license to the officer with my drivers license. Normally, I get a "I don't need that", followed by thanks. Once in my semi I got a "what's this". When I explained once he ran my CDL it would pop up and I did not him concerned, I got a thank you.
By the article the wife made it much worse.
Bottom line when in Rome ........