Many juvenile Cape May warblers do indeed show a little more colour in late-summer or early fall but some can be quite drab, especially females. The parts that might otherwise be a pale, yellow wash, seen between the gray streaks, tends to present as merely lighter gray instead of yellow. Tell you what ... just do a net search of juvenile Cape May warbler (images only) and there will bound to be some pretty drab birds among them. I remember seeing some really drab examples at Ashbridges a few years ago. That sighting too occurred in August. The only other warbler with a face like that that might be passing through this early is a Pine warbler. The off-white discontinuous eye ring and line through the eye also resembles an juvenile Orange-crowned warbler but they wouldn't be passing through until Octoberfest, or later. I always leave a little beer out for them ever since one visited my garden. "Prost" Noch ein bier, bitte.