Is this a US error?

I have a 2011 P $1 coin. It is the Ulysses Grant. Looks like a sideways S between 2011 and the P. Is this a good error? The pictures aren't that great but I took them with my cell phone. And it is circulated.

First this that I would do is to examine the whole rim in attempt to find some other extra images. Just to check the hypothesis of the double inscription making on the same blank. This type is among the most common spoilages in money making.

Then I'll try to look carefully at about 100 pcs of 1 dollar president coins. Just to find something similar or other peculiarities.

And finally make a decision based on checked material.

Sorry, it's a program not an answer.

I will do that! Thanks, again. cyprusalexander.