Hi - I'm a new user and discovered this when attempting to view simple models in Google Cardboard (following the directions here). Sometimes, the images display properly, like this (meaning they take up the entire height of the screen when the phone is held in landscape mode)
Other times, the image appears squished vertically, which then makes the image really distorted when you view it through a headset:
It took me a few tries to figure this out, but after trying to reconstruct the problem - it looks like it happens if you launch the VR view when the phone is in portrait mode (i.e. append "/embed?cardboard=1" to the URL then click the play button that appears on the model) then rotate the phone to landscape mode. The image doesn't resize properly. If you rotate the phone to landscape first then hit the "play" button, it will take up the whole screen.
This is probably minor, but it had me confused for a while since I usually operate my phone in portrait orientation and only switch to landscape right when I need to stick it into the VR headset. Thought I'd post it here in case I'm actually doing something wrong or if it's a bug.