happen to my 14 silverado 5.3 as well but around 65k making an horrible knocking noise when on v4 mode, took to dealer said it was lifter collapsed, took the same amount of days for parts, under warranty and got a free loaner ( 19 high country literally made me want to get that truck lol..) but repair took about 4 days due to the fact they had to repair both sides of lifter they now telling me i should be good for another 100k. i had the same quotation “how is this happening so early in the truck?” they reply “ premature aging, somewhat a common problem on these trucks” like what??? the truck feels so much better now and the shift to v4 doesn’t feel that bad, going to do an oil change too just so i can have a better piece of mind knowing everything is fine there... i wouldn’t be that much worried... i’m guessing just one of the few that got unluckily with the bad lifters but i will be getting extended warranty and honestly if this problem happen right now who knows what can happen later on that’s why better to be safe than sorry!