There is this question and answer today on Guy's forum:
Q: [...] My only worry is MK’s physical motion on stage. I see him walking very, very slowly and I ask myself if there are some back problems again. As it is a long tour, I would suggest the stool as a full show equipment since I have seen MK playing better than ever while sitting down. Is he allright? [...]
A: None of us are spring chickens but yes, Mark is in a good place…and getting better thanks.
Whatever that means.