it's a question of (something)
It is a matter of something; it is actually or ultimately about something. If it's a question of money, rest assured that our firm is willing to pay you whatever you ask for the service. It isn't about how this might help my career. It's a question of morals.
question of something
a matter of something; a problem of something. It's not a matter of not wanting to go to the opera. It's a question of money.