2007 Tahoe engine dead 117k only

[upartz]

Bought 2007 Tahoe, had 77k on it, I drive a lot, put 40k on it in 8 month. Came back friom one of my trips, woke up in the morning and some noise coming from an engine, took it to the dealer, they said need new engine. 6k for rebuild engine with 100k warranty. I dont understand how I ended up needing new engine, vehicle was well taken care of, religiously changing oil, all fluids changed on time. I am not towing, mainly hwy miles, good gas 91+ only. Any suggestions