Re: However, being transported in a user's pocket is a normal use-case for a phone
Indeed. But it's not clear if it was placed carefully in a pocket, or for instance, stuffed in a back pocket.
It DOES sound like the phone is more delicate than some, but that may or may not be to the extent it should be considered a problem. A handful of people reporting the issue out of 10 million is not a big enough sample.
It could be a bad batch with a common fault, even.