Good point. As others have noted, there have been three in the Bay Area the past few days, and I think at least three in Southern California this year. There were maybe 7-8 last fall too, but historically they haven't been quite this regular.
That said, the report that Jeff referred to ( https://ebird.org/view/checklist/S60251357) doesn't mention any yellowish tones on the underside, and hinted at a very strong face pattern. Red-eyed Vireos are much more common on the CA coast than Yellow-green, and I think Red-eyed would be more likely to be singing than Yellow-green. Therefore, I doubt the Newport bird was a Yellow-green.
Yellow-green Vireo is definitely overdue for Oregon, though I'd bet that Neah Bay will beat us to it.