It does look like you might have a hinge there, hard to tell for sure, seeing as how
this is a board stave you can use caliphers to check the thickness and see if its noticably thinner
at that point. Other than that its looking pretty good. If your at 40#@24" why cant you make 40#@28"
Slow down now and remove wood evenly with plenty of exercise in between wood removal.
How about a unbrace side profile