I bet you are right and that is a and nothing else. That red-orange color is just the result of the squash being off the vine and in the light for awhile. Many green squash and ornamental gourds take on that exact coloring as they get older. Since this was in a market I image it has been moved a lot but you can see that one side has more of the red-orange color than the other and near the stem it is still green. In my experience green squash often take on this nonuniform coloring because of one side being primarily exposed to the light. Also based on the date on the photo I imagine you bought this recently, but most squash would have been picked months ago which also makes me think this squash is old (but of course still good).

I see the pattern on the skin that is similar to a one-too-many but if you look at a green they also have this pattern. Have you ever seen the pumpkin {{gwi:847046}}? It is very similar to the {{gwi:847048}} but much more red than white.