x15 cold idle boost fluctuation.

[marek4792]

2019 X15 Performance 430k miles, EGR tuneup at 410k miles. So when starting the truck for the first time, it will idle with steady boost in its SCR warmup mode (not demandated) and about a few minutes in the turbo will start boosting up and down 2-3 pounds whistling on and off until bumped into hi-idle, engine rpm is steady the whole time and doesn't surge at all.
Just wondering if this a normal thing I'm overthinking or do I got something tweaking out besides the nut behind the wheel.