terracottas dont stick to sticky pistons

so basically i was messing with pistons and terracotta when i realized something strange, when a sticky piston (and i'm sure it was a sticky piston) pushes a terracotta, it doesn't bring it back.
i'm sorry i couldn't get any screenshots but i'll try to redraw it with text
Button=- unactivated redstone=' activated redstone" piston=P piston head=I Terracotta=B

• ' ' ' PIB
• " " " P IB
• ' ' ' PI B