It is in fact a Lightning Bug. If you look in the inventory in 16w21a snapshot, you can see the shadows are on the right instead of the left. But when crafting, the item (chest) appears to have a shadow on the left. This happens because maybe the item wasn't changed when you crafted the item(chest). This might be fixed in the next update.
Respawner
It is in fact a Lightning Bug. If you look in the inventory in 16w21a snapshot, you can see the shadows are on the right instead of the left. But when crafting, the item (chest) appears to have a shadow on the left. This happens because maybe the item wasn't changed when you crafted the item(chest). This might be fixed in the next update.