JC3Audi

Recently purchased a 2013 Audi A5 with 70k miles, everything checked out with independent mechanic in pre-purchase inspection....buy the car and less than 3 weeks later I'm told it needs a new driveshaft. Mechanic says it's an internal issue that was undetectable in inspection. Anyone else experience driveshaft issues on their Audi or A5? Mechanic and dealership both say this is a very uncommon and essentially unheard of issue with Audi, especially with only 70k miles.