In granite, trace amount of uranium can be a concern. How significant of a concern would be a nice paper napkin exercise. Other than that, granite will radiate (if it does, at all) in the form of β- at 1.3MeV as a result of potassium-40 decay. The metal canister of a 35mm roll will effectively block it. The remainder will be mostly (again, if at all) radon. Radon emits α radiation, which is effectively blocked by e.g. a sheet of paper. Seems to be they're quite insignificant threats compared to cosmic radiation.
I think there's was back in the 1960s an educational case study that involved 'mysterious' fogging of film at Kodak. Students were supposed to show their analytical skill by tracing the origin of the problem, which turned out to be long-term storage of stock inside a granite cave. I don't know to what extent it was a realistic case. It was apparently sold as such to the students. Well, even if there was a little stretch of the imagination involved - never let reality get in the way of a good story.