Inventory Texture Bug

Put the summary of the bug you're having here

What I expected to happen was...:
Normal piston, sticky piston, and beacon block textures

What actually happened was...:
Very noticeable dark textures on (sticky)piston face mini block inside beacon

Steps to Reproduce:
1. Open Inventory (E by default)
2. Click Redstone Tab
3. Look for Pistons/Sticky Pistons
4. Click Miscellaneous Tab
5. Look for Beacon