Alternator/generator/regulator problems of the 2015 Toyota Corolla

I want to report that I found a loose bolt poking out of the drain hole on the rear passenger door of our 2015 toytota Corolla. It was oriented in such a way that only the threaded end was poking out the hole and held inside the door by the bolt head. I took it to the dealer and as a courtesy they removed the door panel and determined it had come from one of the window parts (regulator or motor). They reinstalled and tightened the bolt. I read on the internet this was a serious problem with previous Toyotas and created safety concerns. This may be a continued problem with Toyotas. It was obviously a very small chance that the bolt actually landed in a fashion to partially stick out of the drain hole so I was able to spot this, so I can't help but wonder if other window bolts in the car have, or will, come loose and fall into the interior of the doors without detection. This may also be the case with many other Corollas sold. Bolts that become loose and fall off of window parts could lead to inadvertent and dangerous failure of windows on the road. I suggest you investigate this potential safety issue.