Looking closely at a Redstone Torch will reveal a small overhang. Looking even closer will reveal a small gap after the overhang. It is recreated everytime you place a redstone torch. But to see it closely, you need to put a fence (to get you as close to the torch) and the redstone torch. You then need to sneak around the fence and look for the overhang and gap. Sorry if this is a duplicate or if the instructions weren't clear for you.

I think the Redstone Repeater and Redstone Comparator borrows the Redstone Torch block texture and this bug might also affect them.