If whoever was giving you a treatment of some kind did NOT see the entire needle come back out of your port, then they should be assuming that the needle IS there, and that the integrity of your port has been compromised, and that you might be at risk for entry of a foreign object into your blood stream or surrounding tissues. I would demand that they do whatever they have to do to verify that your port either is or is not safe. If it's not safe, they need to replace the port, at no charge to you.
Not necessarily what you want to hear, but were it me, I would not be messing around with the possibility of having any part of a needle lodged in and then breaking free.
If they say there is nothing they can do, seek a second opinion, and consider talking to a lawyer.
Sincerely,
Tre