Raised pattern of Washington's coat. At first thought it was a finger print. Sorry not at home or would have provided full both sides.
I believe this is slight bleed through of the ink during the printing process, I would say "yes" but it's so minor that I don't believe this would cause extra value on the bill. Just my opinion, hopefully others here can throw their opinions in as well. Ill say this, love that serial tho!
I think that is simply ink picked up from bills underneath and above this note in the stack. For some reason quit a few one dollar bills appear to have a fingerprint on the back which is actually just an ink transfer from the front of other bills in the stack.