This can happen from time to time and is the result of general wear and tear.
To resolve, the door can be lifted by loosening the allen grub screws on the hinges – lift the door and retighten.
If unsuccessful sometimes the silicone packings inside the hinge may need replacing which can be arranged if required. Please get in touch with our Customer Care team if unsuccessful with the retightening.
Below is a video with some useful tips;