Are the Warblers Gone?

I'm not completely certain, but it appears that another springtime landmark has just passed: our Yellow Rumped Warblers have (probably) moved on.  I have seen no signs of them since the 15th.  But I have also not been around to see as much these past several days.  Such an early departure would be unusual.  According to my logbook, my last photos of the season showing YRW's have all been about two weeks or more away, namely: April 2, 2011; April 5, 2010, April 2, 2009; and April 28, 2008.  But the season is strange, and just perhaps mid March has been it.  I'll keep watching, of course, but what I saw yesterday and today looks mighty quiet around the suet feeder.