lionseekerThanks for letting me know. I know the JDM's do not have a warranty outside of Japan, but I always assumed that models available in the US would have a valid warranty card. I had a Prospex Solar Diver serviced here in Chicago (authorized Seiko dealer down the street) and I had bought that from an online store in Asia. They took the warranty card and simply serviced it, no questions asked.
SkipPeThere is a rule that most respected watch brands manufacturers use - the warranty is effective only if the watch bought from authorized dealer or distributor for the particular world's area. If you bought from an authorized retail store the warranty card must be stamped and signed by the dealer, if it is from online store it must be on the list of the authorized online distributors.
I thought Seiko might have a similar policy, however Seiko USA website says you simply must present a warranty card and the proof of purchase to Seiko authorized service. http://seikousa.com/watch-registration