Why not? Was his estate probated? If not, why not? If so, who was the executor/administrator of the estate?
Most importantly, how did you and your uncle (and apparently your cousin as well) hold title? As tenants in common? As joint tenants? Something else?
If his name is still on title, then I'm skeptical about the accuracy of this statement. If, in fact, she had inherited his share, then she would have received (and should have recorded) a deed from the executor/administrator of his estate that transferred his interest to her.
FYI, the term is quitclaim, not "quick claim."

