Saw this story on reddit, had my own similar experience.
I bought a townhome in 2009 that I now use as a rental property. Last summer when I was visiting the home I noticed the floor in the kitchen had sunk a couple inches. I'd heard previously from my neighbors that they'd had the same problem.
When I bought the home, the builder had given a 2/10 warranty which covered the any defects in the foundation for 10 years. I decided to pay the $200 to submit a claim and have them inspect, fully expecting they'd find some reason to deny my claim, but they didn't.
Today I have a check in hand for $38,000 and a bid from a contractor to make the repairs. If I hadn't thought to check my warranty or if I'd waited even 6 months my warranty would have expired and I would be paying that out of my own pocket.
Don't forget to check to see if your repairs are warrantied.