I agree, I have a feeling he just wanted to hang it up. I bet the whole band does since they are doing this Epitaph tour to begin with. They are one of the oldest rock (rock as in the umbrella stratum that metal sits underneath -- back off nerds) bands in existence after all, at some point, you just have stop.
If it was a health thing, there'd be alot more insider press like how everybody basically knew RJD had something bad when the H&H dates got canned and how the Polish media basically leaked that Nergal had leukemia.