Yes why not a Hume's Warbler, the dark legs are good for this species,but the plumage I guess is not enough washed out. I think that without its call it will be hard to ID it certainly. I let other people with better experienced of the species give their opinion. But I'm not sure both species can be separate in the field without hearing the call. I think that even on hand it's impossible, but since this bird is in very fresh plumage maybe not.
Jonathan