2014 Santa Fe transmission "clunk"

My 2014 Santa Fe transmission "clunks" when automatically downshifting. This happens when driving at a constant speed around 45 mph and on upgrade with the engine/ transmission cold ( within 10-15 minutes of starting). While going uphill around 45 mph and applying enough pressure on the accelerator to maintain a constant speed the increasing load on the transmission causes it to downshift, which is normal but insread of downshifting smoothly it does it with a noticible loud "clunk". This only happens within 10-15 minutes of driving, after the engine/transmission warmsup it down shifts smolthly. I have taken it to 2 Hyundai dealerships and neither one is able to recreate the clunk. It is approaching the end of the warranty period (100,000 miles) and Hyundai customer service says there is nothing they can do.