Molting, Mounting, Or...????

[KARy408]

Can someone please tell me what this looks like? Discovered before bed last night, as the girls were all just pruning:

Is this normal? Am I wrong to be alarmed? Could she be beginning to molt, or are the others in the flock picking on her? Is someone getting out of line?
Any thoughts appreciated! I started a much more detailed thread last night, but I think it was too long, so I'm keeping this one short! Thanks!

 

[KARy408]

Update: today she's looking and acting pretty normal. There's no exposed skin or anything, but the feathers do look thinned out a bit in that spot.

I'm thinking: Molt, right?
Is this going to trigger my other girls as well? Bummer, we were just really getting going with our eggs...