The United States Postal Service is an independent agency of the United States government responsible for providing postal service in the United States. One would think that its administrators would understand flag courtesy.
Here are some samples of “Forever” stamps of the past.
As can be seen above, all of these display the flag with the field of blue with the white stars in the upper left, as prescribed in the guidelines.
In the most current stamp, there is a departure. The field of blue is displayed on the right, obviously because the flag is being blown to the left.
I am curious as to why this image could not have been flipped horizontally in a photo editing program to have the flag blowing to the right. This would place the field of blue in the upper left. I did it (below).