When an observer block is placed, it automatically sets its "powered" state to true. This can be see when looking at an observer with f3 mode. However, when placing any block ON the sides, top, or bottom of the observer, it will then realize it should be off. The observer does not realize it should off if a block is placed NEXT to the observer. Also, when pushed by a piston, observers will once again give a false "powered true" state. However, when retracted, it will realize it should be off again. This does not affect the behavior of the observer as far as I can tell, but I believe the issue is caused by a work around while recoding the observer for 16w41a.