Thanks, Rod!
Yes, that commemorative cover confused me at first during my search for the correct stamp. Then I realized that they were simply using the Maine Statehood stamp because it showed a lighthouse in Maine (i.e., representative of the Nubble Lighthouse).
The Maine Statehood stamp is actually based on a painting by Edward Hopper entitled "The Lighthouse at Two Lights". That lighthouse is at Cape Elizabeth, Maine.
Here's link with some basic info: