2006 Tuburon SE thrown rod/piston

Hi,

I bought a 2006 Tiburon Se manual last month it currently has 93,000 KM (55,000 miles0... I immediately changed the oil and did a safety check the only thing that needed work was a leak in the power steering. I have put 5,000 km (3,000 miles) in month because drove partly across the country. I was driving on the highway in 5th gear on a flat road at 160 kilometers (100 miles) it was 7:15 am clear on roads. I heard a bang and the car started smoking I pulled over right away and had it towed in. Immediately, before it happened car was fine I had been on the highway for an hour with speeds between 120-160 km (60 -100 miles). There were no noises nothing strange. The mechanic told me that I threw a piston/road through the engine block and/or manifold and needed a new engine. Is this my fault for going 160 km (100 miles)?... the car was not near read line... I am confused.. the oil levels should have been fine. The warranty is 100,000 km or five years