That makes no sense. Did you check if a bug was submitted? Sure sounds like one. (It's not realizing it received -C63 from the command line when it sees it on #!.) All my unix systems all have 5.8.8, and they don't exhibit this problem, so I can't do much more for you.

Update: See perlbug RT#59652. I wish I had 5.10 to revisit the issue.