There is no inheritance problem

Observe

$ perl -MDateTime -le " print DateTime->now->from_epoch( epoch => time
+ ) "
Can't locate object method "_normalize_nanoseconds" via package "2011-
+10-13T13:33:26" at C:/perl/site/5.14.1/lib/MSWin32-x86-multi-thread/D
+ateTime.pm line 253.
[download]

from_epoch is a class method

If you consider this a bug, report it upstream