Without any other pictures to go by, the only other details I have are:
1 This was not the smallest warbler I've seen.
2 I haven't seen orange crowned warblers in my yard before. That would be a new species. I have seen Nashville warblers here, but usually in the upper reaches of the canopy as opposed to down in my little redbud tree, where this one was flitting around.
3 I remember the bird being olive/yellowish from the side, but the wings seemed a deeper shade--almost brownish.