Every time I unscrew my pen, the cartridge comes out together with the barrel

Hi everyone, I'm using a Faber-Castell Hexo fountain pen, and whenever I unscrew the barrel, the ink cartridge comes out with it. I should mention, I am using the longer ink cartridges, but they are made by FC, so this is still unexpected for me. Is this a sign that my pen is faulty, or is it not a problem?