Now question is, what to do with the remaining hairline crack along the fingerboard (as Howard said, must have been caused by the fretboard wood shrinking):
That portion is over the neck joint block so I cannot clamped it or flex it. Considering the consistency of the hide glue, I doubt I'll be able to get anything in the crack. So ... I was thinking that in this case to use a very, very thin layer of super glue (StewMac #10) just to seal the wood and prevent the finish from flaking. Will that work ?