I know this is an old thread, I just want to add I bought the iPad Pro 128gb, and it does the air gushing thing if you press on the screen. I think this is normal since all the floor model at the store do this. Probably there's little support under it since it's filled with battery. Circuit is tiny on this.
Mine does creak if the iPad is picked up from sitting on table.
I did get a replacement from the brown box. The replacement does not creak, but does gush air a bit. They all do this, so I think this is by design. Those who said theirs is solid, you probably not hearing it or not pressing the screen harder.
Do note that the replacement fixes the gesture issue that I was having. It was not doing 5 finger home gesture nor the swipe to switch app, I have about 30% success rate doing it. I thought I was doing it wrong, yet this is not my first iPad. With this replacement, 5 finger gesture is 100%. Something people with gesture issue should know.