If it was authentic, I would be shocked. If you look at any of his signatures, the curve around Stephen is wrong - the arc is too pointed and it does not encompass the S, the T & H should be the same height or higher than the S, the K has too much of a loop and it almost always should be outside of the Stephen "swoosh", the end of the "swoosh" line usually doesn't go much past the K, the P and G are totally off and it doesn't seem to be written at the same angle Stephen signs. Those are the things that stick out the worst.
Even is this was rushed, it would still maintain those same traits. Forgeries are meant to emulate the original or they wouldn't be forgeries. If you paid a lot for this, I would try to go thru Ebay to get your money back.
Wow, thank you. I will definitive try to get my money back now..