Several others on Twitter heard your same notice:
http://twitter.com/#search?q=tsunami%20warning
Tsunami? No. Mistakenly sent message just a test, forecasters say
A mistake during a training exercise caused a message to go out to television stations this afternoon that a tsunami warning was being issued.
Ryan Sandler, a meteorologist at the National Weather Service office in Medford, said there was an in-house training exercise for issuing emergency weather warnings. Someone neglected to push the buttons that prevent the emergency message from going out to television stations.
snip
http://www.mailtribune.com/apps/pbcs.dll/article?AID=/20090804/NEWS07/908049996