Probably, yes.

Oddly, Lucius considers the opposite true: that Narcissa should have opened up more to him about her true feelings toward him.

Well, Narcissa is dead, I promise, so it would be a trick and a half if she had somehow managed to have something to do with impostor Draco. And if she set a plan in motion before she died, it would be at least seven years back.

And you're right! I hadn't noticed that contrast before.