Hi SantoGC,
It should be ok for you to go to the INS consulate in Seattle. If you have not yet sent your AR-11, they will ask you to fill it and send it. I was in a similar situation. I lived in Denver and moved to Houston and received the approval notice within a week of my move. I had submitted the AR-11 within the first week.
When I went to the INS office in Houston, they stamped my passport and suggested that I fill the AR-11 form. When I said that I had already done that, they congratulated me and I was on my way. Hope that helps answer your question.
Bumble