Carrier/rack problems of the 2015 Kia Motor Sorento

I was driving straight in a grain silo town in kansas (coming up on oakley from colorado springs) and there were no cars around me. The weather wasn't drastically changing and there was no adverse weather. Suddenly, it sounds as though there was an explosion on the top of my car. The fabric partition that separates the sunroof from the interior of the car starts shaking violently in the wind and there was some glass shards that fell into the car. It goes without saying that the incident scared both me and my two kids who were in the car with me. I pulled over to the closest gas station and took a look at the damage (seen in the picture below). As I had the rest of my road trip to accomplish (kansas city, mo), my husband met me in oakley, KS with his car and we made the exchange. I am a very meticulous driver who inspects everything before a road trip: tire pressure, window cracks, interior is intact, drastic change in weather along the trip, etc. I would have never thought to look at the sunroof and even if I did, I'm not sure I would have found anything. If I were driving on a major highway I could write this whole incident off as maybe a stray rock. However, there was nothing around me.

Driving on mild summer day (~70¿). Lightly-packed cartop carrier affixed properly/safely to kia crossbars (installed by kia). Driving on interstate highway with "passing lane" traffic (about 75mph). Running ac at about 70¿ inside, with all windows up. Panoramic sunroof closed, with inner soft sunshade also closed. About three hours into five hour drive. Suddenly, without any visual warning (e. G. , rock, shard), we hear an *explosion* sound from above, along with the sound of glass clanging everywhere and the rush of highway air. I quickly switch my hazards on, decelerate, and pull off the road as quickly as I can. I noticed that no neighboring vehicles as much as flinched during the incident, nor did anyone stop . . . As if nothing appeared to have happened externally from their point of view. When we got out to investigate, we saw that the front major pane of the panoramic sunroof had completely shattered center-out, probably about 2sqft of glass missing. Notably, several edges around the newly-formed hole were upturned. Those are all the details I can remember. My very strong belief is that the sunroof exploded without any external debris involved. The position of the cartop carrier relative to the hole, my vehicle's position relative to other cars/trucks (not terribly close), the fact that I saw no object hurtling toward the vehicle prior to the incident, the fact that no object was found in between the roof and the inner sunshade, the fact that no other cars/trucks behind me reacted . . . All the signs point to something simply being wrong with the vehicle.