I can't say that it's never happened in Dev but I was just out there running multiple reports and it didn't happen but when I ran just a couple reports in Prod it happened. I chose a form from the menu (a submenu) and hit the Print button with this code behind it: repo form rptposbudstg prev noco. Then I closed the report and the form and tried to choose another form from the menu but then the submenus do not appear.

PS. I like your 10 types of people statement!