Not a bedroom anymore when replacing straw with wooden bed

So I built a small wooden house with a straw bed for everyone and gave it to them so it would keep them happy.

Once I was able to build the wooden bed I ordered the wooden bed to be built in the same spot of the old straw bed (the wooden bed appeared as a ghost over the straw bed). Once I did that, the house did not count as a 'bedroom' anymore and all my nobles became unhappy because I apparently took the bedroom away from them. Once the wooden bed was built it counted as a bedroom again. I expected the game to still count it as a bedroom because the straw bed was still there. It was not deleted, it was just to be replaced by the wooden bed.