In all probability it will have been made into a exe with either Indigo Star's Perl2exe or ActiveState's PerlApp. Contrary to what Aristotle said the original source code is not stored internally in verbatim form. It is encoded. Some monks cracked PerlApp in public at A real challenge and then AS changed the encoding. So the encoding algorithms have changed over time, and thus the decode depends not only on which program was used but also which version. There are similar published decrypts on Perl2exe if you Google for them.

Of the free perl tools PAR does store the code verbatim but is unlikely to have been used based on timing and motivations. The B:: compiler backends basically don't work for anything past trivia so are very unlikely to have been used either.

It is almost certainly possible to retrieve the original source code. It is also almost certainly not worth the time and effort.