I never knew this before until recently, but if you have a mastery selected in the book but not running, and you dump that skill on a stone for whatever reason, even if you put it back on, the timer engages and you have to wait out the 10 minutes. My example is Taming, the book will still say Taming Mastery but when you try to either whisper or combat train you will get the "you are not on the correct path" message. This seems like a typical poor Dev fix to some kind of exploit. Sometimes templates get tight and you have to fiddle with different skills to move things around, especially if your template has both 100s and 120s.