Yeah, i'm thinking they must be old. I bought some in bulk a while back, and still had 6oz sitting around (in the freezer, but not vacuum sealed). So, i figured I'd make my version of a CAP (no corn, though). The beer is otherwise great, but every 3rd bottle or so has an off taste that is most definitely coming from the hops.
I've heard Cluster can smell like cat piss, but these smelled fresh-ish when i used them (it was a lager, so that was like 2-3 months back), and I didnt get that particular aroma at that point. Now, though, theres a faint hint of .... something. I think its kind of funky, but not cheesy. I'm going to chalk it up to the age of the hops AND the breed, and go with fresh Magnum next time