I just got the exact same thing on my '07.5. Went from AV with sticker under the hood to the AX and the overhead display update flash. Like yours, they forgot to do the underhood sticker to AX, although my paperwork says they reflashed it. Owner's supplement looks like a small portion of the '08 truck's Owner's Manual and deals a lot with idling, overhead messages, regen, etc.
As for the overhead flash, my MPG are now pretty much dead-on with the 285/75-17s. Actually, my last hand calc. showed the overhead reading .3mpg low, so that's a big change from it always reading at least 2mpg high. However, I thought the new overhead flash was supposed to indicate when the truck is going in and out of regen and mine doesn't.
Hell, I don't know. Honestly, after laying down over $50K the last thing I really want is to be worrying about all of this crap. Guess I'm a little disgruntled with this whole 6.7L experience since I haven't grown the marbles to up and delete the emissions garbage and run a programmer.
__________________
2007.5 Ram 2500 MegaCab 4x4, 6.7L, 68RFE, 3.73 gears, SLT, Line-X, Snugtop Extra Vision shell, Bilstein 5100s, 285/75-17 Toyos, Walker Evans wheels, Amsoil lube & bypass filter, PML rear diff cover & tranny pan, Dynatrac Free-Spin, Arab's kid's college fund