It has also been reported with previous versions that you couldn't delete a recording that was still playing, so I do not see it as a bug, just a behaviour characteristic.
You will have to learn to stop playback of a recorded programme before starting another one playing.
never noticed it on older versions, i'll try to explain to my 6 year old lad that he must press stop first (he's going through a stage though , you cant tell him anything if he thinks he know how it works)