Placing redstone torch change block it's placed on

When I went into a cave and randomly placed redstone torches on the ground (specifically stone) sometimes the block underneath would turn to dirt. Other times iron ore.

The image attached shows where the blocks changed. All blocks were previously stone. The spots that are dirt that do not have a redstone torch are spots where I had placed a torch and then removed to see if the block would "turn back" to stone.