It's not glue.
There is a metal casing under the wrap.
When metal is exposed to oxygen, it oxidizes.
That's all it is.
It's very very common with Sony VTCs.
It's not a problem.
Experienced vapers who regularly use Sony VTC battery's are very familiar with this.
I agree with all you've said here Bad Ninja, except the oxidation. When I took the wrapper off mine I found no evidence of that. If you or anyone else has found oxidation under a wrapper I would love to know about it. Specially if there were some of the dark spots which mine didn't have. My thought is there could be a different process going on there and it would be nice to know what it actually looks like.