I had the exact same experience. I never found any missile either. Fortunately, my comprehensive covered most of the bill.
The guy that came out to replace the glass told me that the tempered glass windows were extremely susceptible to scratches, as he was gingerly scraping off the sticker on the new glass. A tiny scratch could make the the window spontaneously shatter. He told me that there were a lot of replacements in hot weather due to the glass heating and the stress building to the point of shattering. The glass is designed to break into tiny pieces with square edges to help prevent injuries.
When I was in high school, I used to make an oddity called a Prince Rupert's Drop. It is made by heating glass to the melting point and allowing a drop to fall into into cold water, resulting in a teardrop shaped piece. Because the resultant stresses from the sudden cooling and shrinking were so well balanced, you could hit the drop with a hammer withou breaking it but if you snapped the thin tail of the drop off, it would shatter into dust.
