Rpm Bounce

[GMCSierraSLE1500]

This is all new to me, when I am driving and the a/c is on the RPM's on the truck tend to bounce and you can feel it in the truck while driving, and then again when the a/c is off you can notice the rpm guage bounce but its not as noticeable, I talked to the GM tech locally and he said its normal and that the truck is computered up so anything goes wrong it pops up on the DIC letting you know of any issues, I just want to know if its normal, its a brand new truck 150 miles on it.