Base Size for Nightbringer

I recently bought the Nightbringer model. It was the finecast one so must be recently packed by the GW. What puzzles me is that it came supplied with 40mm Terminator base instead of 60mm as was normal with other Monstrous Creatures.

The question is simple --> Would it be legal for me to play it on the 40mm base?

of course it is. i believe Avatar also got the same question.

Oh.. okay. Same answer with Din. Thanks bro.