I disagree about taking it out of 4x4 without backing up. That's kinda one of the points of having non-locking hubs up front. There's a reason why they call it "four on the fly". You're supposed to be able to engage and disengage it without stopping. That was the point of the design of the system, so people could engage the 4x4 and then disengage it if they ran into a slick or snowy spot on a road without having to pull over, get out, unlock the hubs, then put it in reverse to disengage everything. Personally, I like the old way better because when you unlocked the hubs, then nothing in the front drive line is spinning, which equals less wear and tear on the whole system.
They call if SOF (Shift on the Fly) because you can shift on the fly when using it in appropriate conditions. My comment was specifically aimed at a situation like the one you described being in where you have engaged it on dry pavement and caused wind up, an inappropriate condition. If you are on a snowy or icy road and were in 4x4 but now you are coming to a clear section and you are taking it out, no you don't need to stop and back up.
Remember the description I gave earlier, about drive line wind up comparing your drive shafts to the rubber band on the balsa wood plane? It is accurate. Bobby's description of the T-case as the strongest part of the drive line is also accurate. I have seen vehicles that were accidentally dropped into 4-hi by accident at 65MPH+ towed in with shattered t-cases, broken diffs, and pretzel-shaped drive shafts. And the first one that comes to mind is an F-550.
Now think about what happens to the propeller of that plane when you wind it up and let go. It releases that tension and goes spinning. If you have your drive shafts wound up like that and suddenly disconnect them from each other, releasing that tension, they pop back to normal. And they release that force. And all that force, which was spread over the very strong, full length of the engaged gears in the t-case is, for a split second, held only by the not nearly as strong tips of those gears. This is where physics and geometry are not your friends. PSI is a funny thing that way, because it depends on surface area. Lets say you have 200-300 PSI spread across the surface of those gears when fully engaged. Now suppose that the engaged surface area at the very last moment of disengagment is 1/100th (I am making up number at this point to keep the math easy) of the fully engaged surface area. 300 PSI spread over 100 inches is fine. That same applied force when brought down to one inch will strip the ends off the gears.
The dealership tech probably drained your t-case fluid through a strainer or a coffee filter, came up with little chunks of gear, and then checked to see if a whole transfer case was going to be covered under your extended warranty.
Oh, and for the record, that same instruction book also says that if the system shifts into 4x4, and then fails to complete the shift back to 2wd you are supposed to put the selector back in 4-hi, back up a few feet, and try again. They know that if you wind the system up far enough to motor can't pull the gears apart.