No, I've 5 purebred CL pullets from late June just coming into lay and the eggs are blue from day one. Olive eggs mean a crossbred hen. Sorry.
I've 2 crossbred chicks that came from blue eggs in the same batch and it turned out the breeder had an escaped Splash Orpington cockerel for a couple of days. One is a boy but the other a wee blue/grey hen and she lays cream eggs. So I'm guessing the pure legbar parent is the hen if your chicks came from blue eggs, but daddy was a brown egg laying breed escapee of some kind.