I didn't think I did anything like that, after the first time it slipped/slug-shifted, I made a point to keep the throttle steady and just listened.Just a quick question, cause I know this was an issue with mine.
When you were shifting from 1st into 2nd, did you let up on the gas a bit, and then give it a bit of a boot?
I drove test drove 4 Frontiers in the same day, before I purchased mine, and they all did the same thing, and I couldnt figure it out, it kinda kicks out of gear if you do that or feels like a major slip.
For whatever reason the ECM, or perhaps the Transmission computer, or whatever, learns how you drive. It took about 500 miles before mine stopped doing this, and now things are just fine.
But, given that someone else at least experienced it...I'll give it a bit...maybe it'll shake itself out...
It's supposed to be cold tomorrow too, looks like I have a reason to get up early instead of sleeping in...just to drive my truck and see if it does it again...(though it could do it after work today too, since it's not supposed to get much warmer)