Shifty neck :lol:
Its the laquer crack as the truss rod insert might have shifted ! Since both wood are of differant density, when hard impact of some sort bending occures the laquer cracks.
No worries ...either just leave it or if you can diy ...
....sand down laquer >>> apply supa glue with a harp object along crack>>>dry>>>sand with either 800grit followed 1000grit waterproof sand paper !!
:wink: