It was hanging out with the only other non-killdeer shorebird, a sanderling.
The legs were a lot lighter than my memory of birds in Florida, though this bird's legs are pretty consistent with the pics in the orange Karlson Shorebird guide and fairly close to Sibley. It has a lot of retained wing coverts from last year. I think that the extent of the black neck stripe indicates a breeding male.
With this bird, I've seen more county lifers in the last 4 weeks than I saw all of last year. It makes a person wonder what else is around.