Wishful Junco?

We got home today. Wonderful fun vacation with all our kids and grandkids; but it is nice to be home. I started a load of clothes and then walked around my yard to see what new was blooming; I saw this little junco with nesting material in her beak. I watched as she flew from the downstairs deck, to the tree, to the upstairs deck where a male junco met her. BUT then she flew to the window and stayed there staring at herself as she tried to flew into it. What is happening around here? As far as I know, she is still carrying that material around!!!! 
AND our white breasted nuthatch is building a nest in the birdhouse at our feeder.....and I see no mate around. Is it a "he" or a "she"? Don't know. Is it possible that the male bird that was here a month ago mated with her and an egg is in her???? No, I don't think so. 
Anyway, I am home now and hope to sleep well tonight. I might find time tomorrow to add a few photos from our vacation.