That's not even close to nearby, that's about a 45 minute drive (used to live near there)
Links to Whidbey Island Missile launch info
https://skunkbayweather.blogspot.com/
http://cliffmass.blogspot.com/2018/06/was-there-unannounced-missile-launch-on.html
additional info
The missile came from the direction of Naval Base Whidbey Island (located near Oak Harbor, WA on Whidbey Island)
I looked at the map and only found one thing that kind of looks like a missle silo.
Otherwise, the missle might have been launched from a Sub off the coast.
Sub base Bangor is south of there, and go by this location on the way out to the Pacific ocean all the time.
(had to wait at the Hood Canal bridge for sub crossings many times - I used to live in the area.)
I think I found our D5
https://missilethreat.csis.org/missile/trident/
Don't know how it could be a coincidence….
But… that's one of the few that can reach from WA to Alaska.
The other is a Minuteman III.
Unless there are others not listed that I can't find.
Not entirely sure about the D-5 (they are full Nuclear)
Look for Bangor if you're looking on the map.
I'm thinking it might have been a SM-3
https://en.wikipedia.org/wiki/RIM-161_Standard_Missile_3
That's what I'm thinking… trying to find what kind of Missile it could have been.