Warblers make my head hurt!
The tail is tricky to see, but it goes from a bright yellow UTC to a black block then white ends (just like a Yellow-rumped). I believe I saw it pumping its tail a fair bit too (like a Palmie). It was in a pine-tree the whole time.
Oh, it actually is a Palmie! It just looked “off” to me, but here’s one from Google Images and it’s bang on. I don’t think I’ve ever seen a Palmie at NCBGs, maybe that’s what threw me (and it being up a tree and not on the ground).