Title says it all.
I was playing career mode, accepted station contract, decided to put all not-so-aerodynamic stuff like solars and radial-mounted life support into inventories and attach them in orbit. And after I've attached the first LS container, I noticed that station no longer satisfies the "build new station" part of contract. Detaching the container and storing it into inventory makes the station satisfy that part of contract again.

Quick dig through persistence files tells me that it's because attached part's launchId property is set to zero instead of some decent value, and that part make the contract system think that I cheated by attaching my new station to some previously existing object.