Yes, I had built perl from source with debugging via Potrs (set DEBUG option for the port either in /etc/make.conf or via "dialog" brought up with make config in the port directory); at the end of "perl -V" ...
Characteristics of this binary (from libperl):
I had rebuilt DateTime again (from source, with perl with debugging) in case I might not have removed all of its dependencies. No difference.
I will try later to build perl & DateTime outside of Ports, but does not look like that would help any given the evidence so far.