that is the default vertical skip after the center environment. Try:

[...]
}{%
  \end{center}
  \vspace{-\lastskip}%
}
[...]


Unwanted vertical space before tabular on title page
What are the standards/recommendations for Drush make files that are included in contrib modules? Specifically, should these make files be included by default (module_name.make) or not (module_name.make.example)?

If they should be included, what is the recommended/supported method of overriding/ignoring them? Is there any documentation to point module maintainers to when discussing this in their issue queues?

EDIT: Found this post by jhedstrom from June 2012 recommending naming make files with '.example' suffix. Is this still the recommendation, or have things changed since then?
https://drupal.org/comment/6160018#comment-6160018
