Ageing is mostly a genetic thing I think. Some people age fast, some people stay young until 40, some people stay young until the age of 35 and then age very fast. Also, different features can add to ageing. For example ageing hair, ageing skin, grey hair, nose getting longer, sagging skin, wrinkles, balding etc. So someone can look older due to grey hair but have great skin at the age of 38. (or the inverse). Of course there are cases when procedures made someone look older. But if you're below 30 I don't think one should worry about it.