This is a classic "pikei" plumage bird - a one-year old individual that shows a dark carpal bar and dark gray outer primaries (not 2-3 black outer primaries as would an adult). Hatch-year (juvenile) LETEs never show yellow bases to their bill.
These one-year old birds mostly remain on their wintering grounds (we think), but annually small numbers return to the breeding areas, especially late in the season. They may engage in limited courtship behavior - which is almost surely what this individual was doing - but are not known to progress to the point of actually laying eggs.
