Egwene knows who the black ajah are (most of them anyway). If Egwene does not make an effort to let Rand know of the black sisters in his entourage will Rand have cause to be mad at Egwene?

I think he will have cause to be angry with her, especially if more black sisters cause him harm like the one (I forget her name) that helped Semirhage.

Nonetheless, I also think that realistically Egwene will make an excuse like "Aes Sedai is Aes Sedai business." And she'll try to argue that it isn't any of Rand's business.