I call it 'grousing'...and yes it's prelude to laying in this case.They're just walking around crabbing, best way I could describe it.
It may continue for more than a few weeks, or not.
Sometimes new layers have thin or softshells, easy to break in the nest.Hope they learn not to trample all over them.
Ling the nest box with a piece of vinyl of a feed bag or something can make cleaning that mess up fast and relatively easy. You can lift the whole thing out and won't have to scrub egg stink off the nest box itself.