You could always simply state the gun is just the way you received it. You have no idea if someone else did anything. You never took it apart so how could you be expected to know a thing like that. Except.....you posted what you intend to do all over the internet along with your own suspicions that it could spell legal trouble.
I see no real possibility that the common .25 cent trigger job and a NY1 trigger could be used against someone, but proceed at your own risk.
"A Liberal is someone who doesn't care what you do, as long as it's mandatory". - Charles Krauthammer