EDIT: This behavior is due to Quasi-Connectivity. It likely "works as intended".
In 16w44a, Observers are meant to output a 1-Redstone tick signal (2 game ticks). However, this is not the case in a downward-flowing Observer Chain, without other blocks.
In the screenshots below, both foreground Sticky Pistons should only push or pull the Emerald Blocks with each pulse.
But the left-side piston pushes and pulls with the same pulse and retracts later than the right piston.
The left-side pulse was longer than the right-side.