In the versions (before the current and the last previous version) it was possible to close 1P for a while (also for days) and it was possible to login again only with the PIN code. The only important thing was not to close 1P in the background process. Only when I closed 1P also from the background process, then it was necessary to login with the master password.
Now with the current version (and also with latest version before): If I start 1P from the background process again, I see often (but not always) only the German message "Beenden" what means "Closing" and the window is closing in the next moment. I have to start 1P again and input my master password.
I like more the way of 1Password for iPad. There I have one time the possibility to insert the PIN code. I think one time is really often enough! If it is wrong I have to imput the master password again. The really big plus of the iPad version: I can input the PIN code also if I closed 1P from the background process. I think this is very comfortable.