Shama-il Tirmidhi Chapter 005, Hadith Number 004 (039).
Hadith Section/Book: Shama-il Tirmidhi Chapter 05. Appearing Of The White Hair Of Rasoolullah
Ibne Umar R.A. says: "Rasulullah (Sallallahu alaihe wasallam) had about twenty white hair".
As mentioned above this is not contrary to the other ahaadith.