This bird is closely similar to a MacGillivray's Warbler and a Connecticut Warbler. They all have gray hoods. Neither the MacGillivray's Warbler nor the Connecticut Warbler is documented in this part of the US. MacGillivray's Warbler is far to the West and the Connecticut Warbler is far to the East.
The remaining similar warbler is the Nashville Warbler.
See here for a comparison.

This bird appears to be a mature female.

"F. similar to m., but paler gray hood; no black mottling on upper breast; thin, broken, whitish eye-ring on some ..." (Donald & Lillian Stokes's The Stokes Field Guide to the Birds of North America, p. 631).

This is a second view

Lockwood & Freeman (182) write of the Mourning Warbler, "Uncommon to rare migrant in the eastern half of the state and very rare to casual in the western half. Mourning Warblers are circum-Gulf migrants and therefore rare on the upper coast in spring. In general, they are much more commonly encountered during the fall."

Picture taken with a Nikon D90 using a Nikon 400mm f/5.6.

September 28, 2013.