I have had this issue since day 1. It's been in three times and I even had the service manager (head guy) ride in the truck with me. He acknowledged the bump but told me it is a characteristic of the 8 speed transmission. The 9 speed in the Pacifica is worse. He had them check for the TCM update that was spoken of, it was flashed. I double checked about the Pacifica and there are complaints all about it. He told me that the trans is a giant computer that shifts fluid. Once the truck learns how you drive consistently, it adjusts to your driving. But if you have a day where your lead footing it, the trans will have that 2-1 bump delay, because it's trying to anticipate which gear and part of the power band your foot will demand before you start accelerating. This reduces the "lag" time at acceleration. If it's wrong, when you put your foot on the pedal, it will quickly shift to the right band, causing the "bump" to meet your foots demand.
That was 3 almost 4 months ago. Since then, I've noticed it maybe a hand full of times. And wouldn't you know, it's usually when I am driving it more aggressively then I normally do at acceleration.
Just my experience/opinion on the matter.
