When you place a texture onto a BSP and resize the BSP, the material/texture is skewed to the size of the BSP rather than staying at the scale it originally was.
You can resolve this by selecting the BSP face that has been skewed and press 'apply' next to 'scale'.
1. Create a new project
2. Add BSP to project
3. Add a texture to BSP
4. Scale the BSP
Head over to the existingAnswerHub thread and let us know what's up.