Broken rendering in osmarender, have I done something wrong?

I have tried to correct the coastline at spåkenes, but when I view the rendered maps,
a big gray box has appeared in the sea, covering a part of the coastline I corrected.

Here is a link to the affected area.

Have I done something worng?
And if so, what have I done wrong,
and how do I correct it?

PS. The rendering error is currently only (shown?) in osmarender,
as mapnik takes several weeks to update the coastline.

It seems the problem is rectifying itself.
It’s not fixed in all visible zoom-levels yet,
but several zoom-levels are correct now,
so the problem seems to be solved.