While I certainly commend you for your diligence -- and perhaps you've already considered this -- but it is possible that your module sensitizes a bug in perl 5.8.1. The CPAN Tester results for Chess::PGN::EPD (0.28) currently show PASS (132) FAIL (1) with the only fail on 5.8.1.

I also looked at the reports for the previous 10 or so versions of this module, and there are no results for perl 5.8.1. It would have been useful to have at least one other data point, but no such luck.