Commencement of laying will cause all sorts of havoc in the flock, they are surging with hormones, not sure what's coming out of their butts, so are all a bit unstable.
The pecking order is fluid, ever changing...even established flocks seem to like a pecking party at roost time.
Give them a month or so, be patient and try not to read emotions into every little thing, and they will all probably calm down considerably.