A couple years ago an ISP trooper did the same thing at Lowes in Fort Wayne. The city police came and got the weapon and the trooper got some discipline.
If I have to use the facilities, I place the weapon in my underwear around my ankles. It may not be sanitary, but I won't forget it once I'm done with the paperwork and leave the stall.
I do to but didn't want admit to it LOL