Thanks - that is what I figured. You can do it accidentally running an incorrect powershell script you run as administrator btw. I have a script that installs programs using chocolatey (that has to run as admin) and makes some configuration changes that I run after clean install and this bit caused it to relaunch as administrator.
reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced" /V StartMenuAdminTools /T REG_dWORD /D 1 /F
taskkill /f /im explorer.exe