A few videos that I took demonstrating how odd the Nissan 7-speed transmission is. This is my '09 FX35. It needed a transmission reflash, and it made the transmission a little less jerky, but you still notice that it's very busy. Here's a few examples of how it goes into this really "low-revving" mode. I'm sure you AT'ers have noticed this before. It's long, but I just wanted to demonstrate it. If you have jerking in your transmission when you're slowing down or it holds gears longer, this is completely normal for Nissan/Infinitis. That's how they're designed and programmed.
Now here's a video of it running normally.