That begs the question, "Why did they come off?" I never had that happen in all my riding. The bicycle mechanics said that was extremely rare. Usually, the problem is trying to unscrew the chain ring bolts when one wants to change the chain ring. They rust. They seize. Why this event happened remains a mystery.
This event reminded me of the importance of small things. These chain ring screws make up a very small part of the bike, but they are extremely important. You never think about them, but they are necessary for the bike to function, at least if you have a multi-gear bike. In a culture that believes bigger is better and small things are looked down upon, I tell you to value the small things.
I reflected also this weekend that sometimes what seems a large problem in our life can be transformed by fixing a small item. As we work with the small issues in our lives and try to correct them, we may see large changes or results in our life. From the book called "The Power of Habit," I remember reading how a messy person made a concerted effort to keep their room clean. It not only made their room neat, but the self-discipline to do so, transformed many different areas of life.
In short, don't neglect the small things.