I agree with most things noted above. In interviews, only being asked what questions you have is very, very typical. EVERY SINGLE campus interview I've been on has been like this. I've been asked very few questions myself and in every single meeting on almost every interview I've been on I've only been asked what questions I have.
I have some of the same feelings devanon does. This gets terribly frustrating, especially in the 2-day interview process and when you are going on several interviews. I get so tired of feeling like all I'm doing is repeating myself and hearing myself ask the same questions over and over. I understand that they know your backstory coming in, but I also feel like it shows some aspects of laziness that they cannot take the time to come up with questions to ask you… I mean do they really know your back story, or did they not bother to read your application, so that is why they don't ask you questions (it has been implied to me from mentors that this is often the case)? That is also what it feels like at times for me. I have tried what socialcurious noted above about not repeating the same questions over and over again, but I have not found that helpful. After 3-4 interviews of only being asked to ask questions, I have covered my bases and when I start asking other sorts of questions that I actually would like to know the answer to (e.g., tuition discount for family), no one seems to be able to answer the question.
I've also only ever had one interview experience where I didn't feel like the program was really interested in me and where they were super nice to me. I even had one interview where the SC chair out right told me the graduate students said after the group meeting I should be hired on the spot…. but even then I didn't get the offer. All of these "clues" are totally meaningless in my experience.