Moving a block with a piston on x or z axis does not break seagrass on the block

When Seagrass is placed on a block underwater and that block is then moved horizontally and replaced by a new block by a piston in either x or z directions, the seagrass does not break but moves to be placed on the new block.  

Not sure if this is intentional, but no other grass, flower, cactus, etc. exhibits this behavior.