stupid piston glitch

i start with a piston that shouldnt be powered
i power it (by placing a redstone block next to it)
place another redstone block next to the extended part of the piston
delete the first redstone block
piston is still powered
even though the only redstone that could power it is diagonal from the block
when i place a redstone diagonally from the piston, in the same fassion but with the piston un-extended the piston remains unpowered
i took screenshots to show exatally what was going on
is this a glitch/bug or is it an actual feature. if it is a feature then it is a dumb one and i suggest it removed as it makes moving redstone blocks nearly impossible without a complex setup, or in lamens terms not verry pratical
also important
only works with upward pointing pistons, witch reaffirms my beleif that it is a glitch
will also work if the redstone block is placed on top of extended piston, not just to the side