1941 nickel

To me on the back of the nickel above the building it looks like a S shaped stamp or I’m i seeing things . I would appreciate your opinion on that.

There is no image but I am going to assume that it is “post mint damage” or “toning” causing an S to show. As those dies for the war nickels we’re not even created until 1942. If it were a 1946 then I think you might have a case for an S Mint mark over Monticello.