Little black lines on model!

I have an issue I cannot find what it going on,

I have made some hedges with transparency on the alpha channel.

I turned the alpha threshold up to 200 to ensure the alpha is working strong.

oh, by the way, the models are made in Sketchup and exported to Collada file and imported to modelconverterx.

i am getting a 1-pixel black line at the top of my hedge:-( hard to notice at first but they really show up in VR by shimmering. i think i might be the edge of the plane from SketchUp showing as part of the model.

anyone come across this?
Thanks to Soarfly Concepts Scenery for helping out. careful of sketchup texture mapping, they tile bleed which if you have no alpha mask at the bottom couple of pixels of your image, it bleeds through if you use the standard snap points, I'll post a video on what i am talking about soon.