Tachometer jumping back and forth while coasting

[RedMed385]

Been noticing while coasting downhill around 40-50mph, the tach will jump back and forth between 1,100 and 1,400rpm. Doesn’t engage any grade braking like previous Silverado. Is this the AFM or TC engaging and disengaging?  Normal or time to take it back in for a flash?  Thanks 

[RedMed385]

Update: 

When coasting and RPM gauge jumping, can feel the engine surging.  Any help would be appreciated. 

[Ld19]

I am feeling this too on my 2019 Silverado LD Z71. I also feel it at around 30mph. Has only 560 miles on it and a little worried. Looking for the same help. 

[Colossus]

Hmm I'd give time to break in, so a few thousand miles.  Let's also see who else has the same issue.