No prob, that bit of twist seems to be there somewhere along the length of most Yew staves I get to play with, just forget the ring following stuff when you get too much twist and shape it as if the wood was all the same (e.g don't differentiate between heart and sap) although don't go so far as to ever remove all of one or the the other...
Errrr, I hope that makes sense.
The last bow I made had a patch about 5" from one end where, viewed from one side the limb was 60% heart, but viewed from the other it was 99.9% heart (I think I just about kept a sliver of sap wood just to make it look right)
That's the fun of working staves, the difference between theory and practice.
Have fun.
Del