http://www.gm-trucks.com/forums/topic/178059-2015-silverado-53-slip-yoke-clunk/
Check out my post, I have the same 2015 truck 6 speed with the same shudder and more, it clunks pretty loud, and it hunts for gears randomly. I got approx 3,6xx miles. I have taken it to the dealer 3 times (documented) for this already, they will tell you its normal and that there is nothing to fix. but my previous gen silverado never did this and it had almost 200k miles by the time i sold it.
I already filed with BBB AUTOLINE and manufacturer is dicking me around, GM asked bbb to deny my claim.
I am debating on wether to go through with arbitration or if i should just sign a retainer for an attorney.