Everyphone has it. But I'm sure some grains of minerals found in sand can scratch the screen.. maybe he found a really small diamond and that one grain scratched his screen.
How do you know every phone (I assume you mean "every G2") has Gorilla Glass? Just because Corning lists the G2 on their website as having GG does not guarantee that every G2 has it. HTC is free to switch materials whenever they want. In fact, they probably reserve the right to change whatever specs of the phone they want, without notice (if they even listed GG in the specs, which they do not). But you are probably right in that many high-end smartphones are using GG these days, so HTC is pretty likely to stick with it for all the G2's.
If you read the older Gorilla Glass thread I posted above, you will see there are other users that scratched the screen with normal use. GG is advertised as being "highly damage resistant", and its harder to scratch than "conventional" glass, but you can still scratch it.
