Rotating mesh causes flicker

[spenceco]

Hello, I've just recently discovered JSC3D and am loving it so far. However, I have come across an issue I don't understand - I am rotating two meshes at once by manipulating their rotation matrixes, which works fine - however, one of the models has a bad issue with flicking, while the other is fine. The model in question is a spray bottle, with two material slots (created in blender). The parts of the model that flicker are all on the material slot that makes the orange label on the bottle. When I remove this slot, making an all-white bottle, the problem disappears. Why is this happening? I can provide the code and models if needed.

[spenceco]

After a bit more testing I've noticed that this issue only occurs upon refreshing the page, not when loading it up for the first time.