Thanks again for all the replies. I do recall some murmurings about a trans reflash needed on 2011 and early 2012 builds. Ours is an early 2012 build, so will have to check that out. Truck had only about 900 miles on it prior to towing, not thinking that should be an issue. Going to call local dealer and see if we can arrange a drive with a tech onboard while tt is hooked up, they have some pretty decent hills right in the area and I have no doubt truck will misbehave while doing so.
Overall we really love the truck and it's more than adequate for our towing needs, but it sure would be nice to use that tow/haul for what it's meant to do.