I bought my first AR-15 at a gun show in downtown Indy. I had to walk 3 blocks to get back to my car and the vendor at the show didn't have a case (and I was out of money to buy one). So I carried it by hand to the car, past multiple groups of people and police.
No one cared in the least.
Duh...you were at a gun show, right?
Slightly different situation than someone carrying it in a random store...