Tom,
Locals would be able to give better context, but it looks like Anna's
Hummingbird is established enough in the Walla Walla area to be a
regular feeder bird for multiple eBirders in the area and has been
present for at least a decade there, although it appears to still be
an exciting yard bird.

Anna's Hummingbird proclivity to wandering and range expansion never
fails to amaze me. A further perusal of eBird data indicates they now
appear to be resident as far north as southeast Alaska. Additionally,
there are records all across the eastern US and SE Canada.

Josh Adams
Cathcart, WA