I haven't driven it again yet.  I'm not sure if they've even run the update yet.  They said they're going to PDI the truck, and if I want to drive it again, let them know.  I will probably go back and drive it again to see if there is any difference after the update - even if it's just for my own curiosity and to let you guys know if there was a change.  On the first test drive, it did it EVERY time I hit 55-60mph, and I did it several times to figure out if I was actually feeling what I thought I was feeling.  If it doesn't do it now, the change will be clear.