17 duramax

Got a 2013 and no.

2016 Duramax; nope

Nope

2017 Duramax -- never felt anything like that.

2016 Duramax. Smooth travel on the gas pedal. It's still under warranty, so take it back and make them prove it's not a problem. When I bought my truck I noticed the tailgate cables were slightly different lengths causing one to be taught while the other was still slack when the tailgate was down. It was a minor issue, but I said something about it. The staff went out and tested a few trucks in the lot and every one of them had the same issue, so it was deemed "normal". Although it didn't resolve the issue, they acknowledged it and addressed it, so I was satisfied.
Also, just a few months after owning the truck I started to think the steering was getting loose. I thought I was just being overly paranoid, but eventually realized that it just wasn't as tight as it was before with excess play in wheel, so took it in. Sure enough, the steering gear box had blown a seal and was slowly leaking steering fluid.
Good luck. Hope it gets fixed.

I remembered reading about someone with a similar problem on the Duramax Forum, so I looked it up.
Here you go. As others have said, it’s a warranty issue.