3.5 months post-op 6,500 grafts: Is thin, small transplanted hair falling out normal, or not?

From 2nd month transplanted hair has started growing and in 3 month most of the bald area was covered but after this third month I noticed that there is some hair fall and the hair density which is there before was reduced. Fallen hairs are very thin and small .are they new growing hair or not.please suggest me how can I prevent this hair fall and tell me those are newly growing hair or not which are falling off. Transplanted hair will grow or not and is there any failure of surgery.