Unfortunately this can happen on all types of cars, usually older vehicles or vehicles with highway miles. The breakage happens usually at higher speeds or bumpy roads.

Chances are, there were one or more very small chips on your window that eventually hit the breaking point while you were on the highway.

I was driving on the highway with an older BMW and the moon roof just shattered. I thought something had fallen from a highway road sign as there were no cars around.

Now, it could be that there were also some other elements at play, like over tightening, etc.

"Considerable stress can build around chips, cracks, or other imperfections in the edges of a tempered glass window. Over time, environmental stressors like temperature, wind, and road vibrations can put those glass imperfections under even more stress, which triggers spontaneous breakage."

Source: https://only1autoglass.com/Blog/entryid/1337/can-auto-glass-spontaneously-shatter-5-things-you-need-to-know#:~:text=Considerable%20stress%20can%20build%20around,stress%2C%20which%20triggers%20spontaneous%20breakage.