How long is the silicone sheet meant to stay in nose after rhinoplasty? (Photo)

After 12 weeks of surgery, I had a cold and as I blew my nose I felt sth came down in my nose. I contacted my surgeon who was out of country and he said it is the silicone sheet hsd left left there to help form my nose and it must remain in the nose for six to twelve months. And that now it has come down I must remove it. I took it out and it was 3 cm long. Question how long does a silicone sheet need to remain in the nose? Did he simply forget it?