So the use/require check is based on whether the module has been loaded by use/require before, and doesn't count the explicit loading of the module at the command line? Thanks for the info - that explains why no warnings were output when the script was actually in use then.

As I hinted at in the original message (but didn't make very clear) the reason that I noticed (and was annoyed by) those warnings was that Eclipse (with the Perl plugin) does compile time checking of code and provides a list of the errors/warnings it can find - this was being cluttered up by those warnings.