So I don't have to go searching for the specific paragraph in perldelta that you are referring to, how about pasting it into your question?

Should you worry about it? I think the answer is yes, if you feel you might be triggering an incompatibility, until you can prove through tests that you've handled it appropriately. How do you identify if it's a concern? Write a test, or a bunch of tests that prove your code does as intended before and after the upgrade.

See Test::More, and chromatic's Perl Testing: A Developer's Notebook, or Intermediate Perl for testing strategies.