birthday.present? && !birthday.blank?

in [Profile.rb](https://github.com/ging/social_stream/blob/master/base/app/models/profile.rb#L94)  the following construction is present

``` ruby
birthday.present? && !birthday.blank?
```

but Rails defines `present?` as 

``` ruby
def present?
  !blank?
end
```

so why to call it twice?
