You could describe rather accurately the work you've done as "getting to know the code base": you've read the code, in order to be familiar with it, and in the process you've refactored it a little.

Provided you are the one who will be maintaining it, this should not cause a problem with the original authors.

Of course adding tests to ensure that your refactoring did not break anything would be even better. Also using perl tidy (with the appropriate options) to reformat the code, and using Perl::Critic to justify your changes would remove some of the "I don't like the way you code" factor.