Confusion

[Simcoe]

I saw this bird flittering around high in a tree.  I am not sure about the ID.  I tried Merlin, but it one of those that just doesn't mesh with AI; I am sure it's not a Blue-gray gnatcatcher, but I don't recall having seen anything like it.  Any direction would be appreciated.

[lovemypt]

Chestnut-sided warbler.. female

[Simcoe]

Thanks for the ID.  I can see a faint bit of chestnut on the side, but there is a "dirty" appearance around the head. Would this bird just be in a late (partial) molt?

[lovemypt]

birds would be in their full spring colours, they woudl have molted before their flight north, will not molt again after summer