Carrier/rack problems of the 2014 Lexus IS350

I bought a brand new 2014 is 350 f sport on August 29, 2014. On or about September 17, 2014 as I was driving home, something hit my windshield and within 24 hours the crack had spread demanding replacement. I paid $1800. To replace with Lexus certified windshield around the 1st of October. On October 10, 2014 as I was travelling home I heard a slight tap. By noon on Saturday, the crack was beyond repair. I have had this new car less that 2 months and I am having to replace its windshield for the second time. I haven't even received the new license plates yet. I am almost 65 years old and have owned 10 cars and this is my first cracked windshield experience. I am thinking that either the vehicle has a design flaw, or more likely the windshield has a design flaw. The repair service confirmed that the is seems to experience an inordinate number of windshield replacements. Even the dealership confirmed numerous is windshield replacements. At $1800 per replacement, this is a serious problem.