I found this the other week... via configure hero screen, I checked Mythic Hero, and played around with it, checking a few things (Guardian Path, etc).
I then went back to Configure Hero, unchecked Mythic, and carried on. (Planning out character for Wrath of the Righteous campaign).
I noticed (much later) my HP were higher than normal!
Looks like some Mythic things were still adding to my character and I had to set the Mythic Path to 'nothing' to actually remove all Mythic stats before unchecking Mythic on the configure hero screen.
Anyhoo, I'll file a bug once I'm able to (
see this thread) but thought I'd post in case others may be unaware and walking with 'incorrect' builds...