No, it's just that it has internal tension such that one side of the board is holding the other in a certain position. Remove that side, and the other will move. You will often see this when you run a board through the tablesaw. The two halves may either bend inward or outward. Usually most of this stress is relieved by the time it is cut as small as a neck blank, but sometimes it isn't.
You could argue that such a board shouldn't be used for a neck, but it's not because it isn't dry enough yet.
I bandsaw the back profile about 3/32" oversize after truing up the top face, but before I do too much else.
If it bows more than than 1/16", it goes in the scrap pile, and I haven't invested a lot of time in it.
Usually it doesn't even bow that much, if at all, but that is the moment when you will see it bow, if it is going to.
If it stays straight after that, any further carving is unlikely to affect it, so after truing up the top face again, I leave it like that until I get the fretboard on and the sides tapered. I usually carve the neck before fretting, but not for any particular reason, and I think I may start fretting beforecarving, because it does seem like it would be easier.