Before getting Cass as a companion, i completed a brother hood of steel quest that had me kill the van graff(sp?) in freeside. So when i got to the part in Cass's unmarked quest about getting the notes from AM and the Van graffs, i went and got them, but got absolutely no reaction from Cass, even when i went and talked to her myself. I even went to Ranger Jackson(according to a wiki page im supposed to turn in the quest there), but he has no dialoge option for it.