Actually ONG does not make money on natural gas, it is sold to you at cost. They make their money transporting the gas. The rate increase is to cover increased cost in maintaining their transmission lines.
I don't remember if it was ONG but I remember reading about a company doing something similar. What they didn't say was that they fully owned the company they bought the product from and that fully owned company was making a pretty profit on the product. A little bit of legal separation can go a long way for perception of benevolence.
I wish I could remember the circumstances better because the next response will probably be to ask for sources. Sorry, it was long enough ago and there was nothing I could do about it except remember the sneakiness.