Post by jmcquownA local bird watcher suggested it's an Eastern Phoebe and that
https://www.allaboutbirds.org/guide/Eastern_Phoebe/id
I'm certain that's not a Phoebe. Body shape is entirely wrong. Phoebe
has much bigger head and bill, longer tail, and not a trace of yellow,
whereas the bird in your photos has a pale but distinct wash of
yellow.
I'm inclined to go with your original guess, Pine Warbler, probably
either female or juvenile. Someone commented that they have "yellow
heads" -- and they do, sometimes. Usually in the Spring, during
breeding season. Like many other species, they adapt more subdued
colors in the Fall.
FWIW, I used Peterson's and Nat Geo's field guides to look this one
up. NG has a drawing of an immature PW that looks very much like your
bird.
Photographs of birds -- at websites, or wherever -- can be misleading,
due to lighting issues and other stuff outside the photographer's
control. I think field guides illustrated with drawings are a much
better way of id'ing birds than photographs -- but that's just me, of
course.
Nice that you got to see one, whatever it is :)