Actually all LCD screens are constructed from multiple layers which are bonded together, so yes, the screens are "glued" together for want of a better description. There are many layers making up the screen, including the backlight/diffuser, two polarising layers with the actual liquid crystal sandwiched between them, for a lot of displays the touchscreen itself is another layer on top of that (on the iphone and ipad mini its built into the front layer of th eLCD, on the ipad 3 and 4 its a seperate piece of glass laminated onto the top of the LCD - i dont think anyone has sliced through an ipad air yet to find out how the lcdis constructed). with all of these layers - what do you think holds them together and stops them falling apart??? ifixit wont have mentioned this since you cant delaminate an LCD display without shattering the very thin glass layers off, they just treat the LCD display as a single unit.
And yes there was a well known issue with the iphone 4 where they were shipping the so fast the bonding agent hadnt fully cured, meaning that anywhere on the display it was slightly thicker, it gets slightly yellowish
for my own personal iphone 4, after a 6 week wait for it to finish drying, it was still yellow so they replaced it.
it is perfectly possible that in these ipads, the bonding agent holding the multuiple layers of the touchscreen together not finished curing