When 3 redstone blocks are place on 3 sticky pistons the middle piston powers.

When I tried to put 3 redstone blocks on 3 sticky pistons the left and right pistons didn't power but the middle on did. I have tried a few other different ways and when it only has redstone blocks on the left and right pistons it still powers the middle one. I am not an expert on redstone and do not know if this is done on purpose or if it is a bug.