Piston Placement [Dupe]

When I was placing a few pistons fast I noticed that they were appearing not to be there (Pic 1). I have seen this bug a few times before in earlier snapshots but not in the latest one (14w31a). When I updated one of the pistons they all came back (Pic 2).
I was playing in creative on a default world.
(Generated in MC 14w31a)