Steps to repro:

1. Open Unity;
2. Create new project;
3. Export attached 'RotatingTreesBug' package;
4. Open 'test' scene;
5. Double click on Terrain gameobject in the Hierarchy view;
6. Go to 'Place Trees' tab in the Inspector;
7. Select 'ScotsPineTypeA.fbx' tree model in Inspector;
8. Paint some trees in the Scene View;
9. Scroll in closer to painted trees;
10. Move the viewpoint to the left or to the right while focused on trees;
11. Observe the trees in the Scene view at the edge border of the SceneView.

Actual result:
After moving viewpoint painted FBX trees rotate while being close to the edge border of the Scene view (see attached gif video).
This behaviour is inconsistent with same tree prefab dropped to the Scene View.

Expected result:
Trees should not rotate or change size when moving viewpoint.

Notes:
- Reproducible in: 5.4.0b8, 5.4.0b7, 5.3.3p2, 5.3.2f1, 5.3.1f1, 5.2.2p4.
- Reproducible on both OSX 10.11.3 and Windows 10;
- Also reproduces in the game view. To see the bug just place main camera close to the painted trees and toggle camera's transform a bit;
- Doesn't reproduce for same tree prefab dropped to the Scene View;
- Doesn't reproduce for SpeedTree .spm models (both painted or dropped.
- For correct repro it's needed to find certain viewport distance in which the bug reproduces (may be specific to certain tree model).