Yup. This was it! We had a rain shower move through while we were at the cabin. It was short and sweet and the rain rained while the sun shined. I thought "Hmmm...I bet there's a rainbow out there!" Sure enough. So I called the kids over to see it. They loved it! They were amazed (it seemed) that they could really see all of the colors. I loved hearing their reactions!
Just today C said, "Hey Mommy! Remember that big rainbow we saw? Wasn't that neat?" I love that a simple thing like a rainbow can bring such joy to a child.