Wait, this is a interesting question, you can revalidate your visa at Washington, but what if you don't have a expired old H1 visa, maybe you can not go to Washington. You may check the website.
By the way, when you extend your H1b, did you file I-129 or I539? You should get a I-797 notice with new I-94 card in the bottom, right? What did they say in the letter about your stamp?