What To Do With The Crack Lines? Pls Advance.

[PeterSeet 0]

There are many hair line cracks in my newly renovated hse (haven't stay in yet).
Can someone advance me what to do cos the ID said he expected this thing to happen after we build up a new store room.

He said that they used the cemical cement and the crack will comes out more faster than using normal cement. and the wall need to settle down for abt 6 mths to let all the cracks comes out then he will come back to do the touch-up work.

Is it truth that what he said? Is that the way ID or contractors practice normaly?