Crack in housing?

[massi.rav]

The reactor is made in 2 halves I think. Has this only just happened?

Could be a bit of a paint defect or misaligned shells.

If it bothers you try sending some images to devialet and get a refund. Is it just that one?

My white ones had a small seam down the middle too.

My white Reactors (I own two) do not have separate halves.
One single monocoque and no visible junction line. 

Maybe the black version is made in a different way?