Shudder between 45-55 w/slight acceleration

Newb to Toyota and this forum, but I recently purchased a new 2017 Platinum X-P demo with 4500 mi and I'm experiencing a slight shudder once the truck shifts into 6th gear (overdrive) running between 45-55 and then give it slight acceleration. It feels like it's missing (plug or COP?). If the accelerator is pressed more than just slightly and the transmission down shifts to 5th, no shudder occurs. I've already had it back to a Yota dealer, not where I purchased the truck, but they deny feeling the issue. I purchased a ODB2 Scanner, but no codes are being generated. I've scheduled a service tech ride along next week to hopefully resolve this problem. Has anyone experienced or is experiencing this described issue?

Thanks,
CMMtn

 

My crosstour does this. Honda has a torque converter fix.

 

I have a 2007 Tundra 5.7 experiencing a transmission shudder as you describe.
Went to a tranny shop and they described it as if I had drifted off onto the rumble strip.
This is a common problem with Tundras and is a torque converter tranny problem.