Torches render as other blocks

A couple of times in the snapshots I have has torches render as other blocks. The first time I was replanting a farm when I saw random blocks of farmland. Upon breaking them, they dropped torches. The other time I was mining redstone ore. When I looked up all the torches looked like redstone ore but emitted light, had no hitbox, instabroke etc. This bug is purely graphical. I have found it hard to reproduce but it has happened to me twice.