does it matter if trousers/ pants don't fit you in the bottom area

[c=7700B2][i]for a male i have a very small bum, and most of my trousers fit ok, but sag around the bum area, they don't fit my bottom as it is very small...is this okay? this is for most trousers i buy...should i not be concerned about it?[/i][/c]