Clearly, the sign was moved, else it would have blocked the man seen next to it, arguably detracting from the balance of the composition. There are also other issues, such as the bricks making up the columns of the building not aligning properly, while the column on the right actually overlaps with the frame of the car in the foreground. In a statement given to PetaPixel, McCurry noted that much of his recent work was shot for "[his] own enjoyment," and he would define his work today as "visual storytelling." Regarding this specific error, he attributed it to a mishap in his studio while he was away and noted that changes had been made to prevent such an event from occurring again. In the meantime, other people quickly found such manipulations in other photos, though these have yet to be addressed.
The problem, of course, is not that the manipulations were made. We manipulate photos all the time, often to the extreme. Anyone who claims not to manipulate photos is either lying or giving away their raws. We must remember that anything, anything at all, that modifies a capture in a way that makes it less faithful to reality is a manipulation. Is cloning a sign to a different location in the photo a manipulation? Yes. How about dodging and burning? How about just a global contrast adjustment or a slight saturation boost? How about even something as simple as an exposure adjustment? I would put it to you that in every one of these cases, the answer is: yes, it's a manipulation.