Does top hen exhibit roo behavior when it comes to nest "building"

We have 5 LF (Brahma, SLW, Dominique, Easter Egger, GLW), in that pecking order. We had our first egg Monday (Woo Hoo!) from our SLW presumably. Today we have 3 (from SLW, Dominique, & Easter Egger)- again presumably.
This morning the top hen (Dark Brahma) was in the nesting box making a pretty nest with the hay. By this I mean grabbing hay that was kicked out the box from the night before (they all sleep in the nesting boxes) and setting it on her shoulder for it to drop into the nest box to make the circular pattern.

The Brahma has shown little signs of laying (she squats submissively sometimes, but there is little comb development & she is a much heavier breed than the others).

Is this top hen/roo behavior? Or am I misguided to think that she isn't one of the ones who layed today?

 

This is what was left for my husband when he went to check on them late am... (if egg size/color give any perspective)