Landscape has a awry vertex

Hi, i made a hexagon lattice for my landscape, and there is a strange error. Can you think what possible reasons there could be?

one of the vertices on the mesh is out of line sometimes, and all the other 100ds of vertices are fine. it’s not always the same vertex, so the mesh model must be ok, but it seems to be mostly on the sides with the zig zags and not the flatter one. when i use normal square plane there are no errors. confusing?!

the code is just a perlin function relative to x,z position.

[20727-treplane+prob.jpg|20727]

it got fixed using mesh generated in unity, sketchup mesh is unreliable!?

my infinite landscape asset is now finished, i just need to make a sales page, its buyable here:

http://frogsbo.com/product/infinite-terrain-unity3d-test/

http://frogsbo.com/wp-content/uploads/2014/01/sc9-150x150.jpg

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